diff --git a/compiler/testData/loadJava/compiledJava/ArrayTypeVariance.txt b/compiler/testData/loadJava/compiledJava/ArrayTypeVariance.txt
index b898af6ef42..f4f7754d760 100644
--- a/compiler/testData/loadJava/compiledJava/ArrayTypeVariance.txt
+++ b/compiler/testData/loadJava/compiledJava/ArrayTypeVariance.txt
@@ -2,5 +2,5 @@ package test
 
 public final class ArrayTypeVariance {
     public constructor ArrayTypeVariance()
-    public final fun toArray(/*0*/ p0: kotlin.Array<out kotlin.Any>?): kotlin.Array<kotlin.Any>?
+    public final fun toArray(/*0*/ p0: kotlin.Array<(out) kotlin.Any!>!): kotlin.Array<(out) kotlin.Any!>!
 }
diff --git a/compiler/testData/loadJava/compiledJava/ClassDoesNotOverrideMethod.txt b/compiler/testData/loadJava/compiledJava/ClassDoesNotOverrideMethod.txt
index 11573442a97..70f617a4180 100644
--- a/compiler/testData/loadJava/compiledJava/ClassDoesNotOverrideMethod.txt
+++ b/compiler/testData/loadJava/compiledJava/ClassDoesNotOverrideMethod.txt
@@ -2,13 +2,13 @@ package test
 
 public abstract class ClassDoesNotOverrideMethod : java.util.Date {
     public constructor ClassDoesNotOverrideMethod()
-    invisible_fake final override /*1*/ /*fake_override*/ var cdate: sun.util.calendar.BaseCalendar.Date?
+    invisible_fake final override /*1*/ /*fake_override*/ var cdate: sun.util.calendar.BaseCalendar.Date!
     invisible_fake final override /*1*/ /*fake_override*/ var fastTime: kotlin.Long
-    public open override /*1*/ /*fake_override*/ fun after(/*0*/ p0: java.util.Date): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun before(/*0*/ p0: java.util.Date): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun after(/*0*/ p0: java.util.Date!): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun before(/*0*/ p0: java.util.Date!): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun clone(): kotlin.Any
-    public open override /*1*/ /*fake_override*/ fun compareTo(/*0*/ other: java.util.Date): kotlin.Int
-    invisible_fake final override /*1*/ /*fake_override*/ fun getCalendarDate(): sun.util.calendar.BaseCalendar.Date?
+    public open override /*1*/ /*fake_override*/ fun compareTo(/*0*/ other: java.util.Date!): kotlin.Int
+    invisible_fake final override /*1*/ /*fake_override*/ fun getCalendarDate(): sun.util.calendar.BaseCalendar.Date!
     kotlin.deprecated(value = "Deprecated in Java": kotlin.String) public open override /*1*/ /*fake_override*/ fun getDate(): kotlin.Int
     kotlin.deprecated(value = "Deprecated in Java": kotlin.String) public open override /*1*/ /*fake_override*/ fun getDay(): kotlin.Int
     kotlin.deprecated(value = "Deprecated in Java": kotlin.String) public open override /*1*/ /*fake_override*/ fun getHours(): kotlin.Int
@@ -19,9 +19,9 @@ public abstract class ClassDoesNotOverrideMethod : java.util.Date {
     invisible_fake final override /*1*/ /*fake_override*/ fun getTimeImpl(): kotlin.Long
     kotlin.deprecated(value = "Deprecated in Java": kotlin.String) public open override /*1*/ /*fake_override*/ fun getTimezoneOffset(): kotlin.Int
     kotlin.deprecated(value = "Deprecated in Java": kotlin.String) public open override /*1*/ /*fake_override*/ fun getYear(): kotlin.Int
-    invisible_fake final override /*1*/ /*fake_override*/ fun normalize(): sun.util.calendar.BaseCalendar.Date?
-    invisible_fake final override /*1*/ /*fake_override*/ fun normalize(/*0*/ p0: sun.util.calendar.BaseCalendar.Date?): sun.util.calendar.BaseCalendar.Date?
-    invisible_fake open override /*1*/ /*fake_override*/ fun readObject(/*0*/ p0: java.io.ObjectInputStream?): kotlin.Unit
+    invisible_fake final override /*1*/ /*fake_override*/ fun normalize(): sun.util.calendar.BaseCalendar.Date!
+    invisible_fake final override /*1*/ /*fake_override*/ fun normalize(/*0*/ p0: sun.util.calendar.BaseCalendar.Date!): sun.util.calendar.BaseCalendar.Date!
+    invisible_fake open override /*1*/ /*fake_override*/ fun readObject(/*0*/ p0: java.io.ObjectInputStream!): kotlin.Unit
     kotlin.deprecated(value = "Deprecated in Java": kotlin.String) public open override /*1*/ /*fake_override*/ fun setDate(/*0*/ p0: kotlin.Int): kotlin.Unit
     kotlin.deprecated(value = "Deprecated in Java": kotlin.String) public open override /*1*/ /*fake_override*/ fun setHours(/*0*/ p0: kotlin.Int): kotlin.Unit
     kotlin.deprecated(value = "Deprecated in Java": kotlin.String) public open override /*1*/ /*fake_override*/ fun setMinutes(/*0*/ p0: kotlin.Int): kotlin.Unit
@@ -29,7 +29,7 @@ public abstract class ClassDoesNotOverrideMethod : java.util.Date {
     kotlin.deprecated(value = "Deprecated in Java": kotlin.String) public open override /*1*/ /*fake_override*/ fun setSeconds(/*0*/ p0: kotlin.Int): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun setTime(/*0*/ p0: kotlin.Long): kotlin.Unit
     kotlin.deprecated(value = "Deprecated in Java": kotlin.String) public open override /*1*/ /*fake_override*/ fun setYear(/*0*/ p0: kotlin.Int): kotlin.Unit
-    kotlin.deprecated(value = "Deprecated in Java": kotlin.String) public open override /*1*/ /*fake_override*/ fun toGMTString(): kotlin.String
-    kotlin.deprecated(value = "Deprecated in Java": kotlin.String) public open override /*1*/ /*fake_override*/ fun toLocaleString(): kotlin.String
-    invisible_fake open override /*1*/ /*fake_override*/ fun writeObject(/*0*/ p0: java.io.ObjectOutputStream?): kotlin.Unit
+    kotlin.deprecated(value = "Deprecated in Java": kotlin.String) public open override /*1*/ /*fake_override*/ fun toGMTString(): kotlin.String!
+    kotlin.deprecated(value = "Deprecated in Java": kotlin.String) public open override /*1*/ /*fake_override*/ fun toLocaleString(): kotlin.String!
+    invisible_fake open override /*1*/ /*fake_override*/ fun writeObject(/*0*/ p0: java.io.ObjectOutputStream!): kotlin.Unit
 }
diff --git a/compiler/testData/loadJava/compiledJava/ClassWithTypePExtendsIterableP.txt b/compiler/testData/loadJava/compiledJava/ClassWithTypePExtendsIterableP.txt
index e0c5ecb760f..aaf0c788b2a 100644
--- a/compiler/testData/loadJava/compiledJava/ClassWithTypePExtendsIterableP.txt
+++ b/compiler/testData/loadJava/compiledJava/ClassWithTypePExtendsIterableP.txt
@@ -1,6 +1,6 @@
 package test
 
-public abstract class ClassWithTypePExtendsIterableP</*0*/ P> : kotlin.MutableIterable<P> {
+public abstract class ClassWithTypePExtendsIterableP</*0*/ P> : kotlin.MutableIterable<P!> {
     public constructor ClassWithTypePExtendsIterableP</*0*/ P>()
-    public abstract override /*1*/ /*fake_override*/ fun iterator(): kotlin.MutableIterator<P>
+    public abstract override /*1*/ /*fake_override*/ fun iterator(): kotlin.MutableIterator<P!>
 }
diff --git a/compiler/testData/loadJava/compiledJava/ClassWithTypePP.txt b/compiler/testData/loadJava/compiledJava/ClassWithTypePP.txt
index 33e6ddc2ff0..9921b69714e 100644
--- a/compiler/testData/loadJava/compiledJava/ClassWithTypePP.txt
+++ b/compiler/testData/loadJava/compiledJava/ClassWithTypePP.txt
@@ -1,5 +1,5 @@
 package test
 
-public final class ClassWithTypePP</*0*/ P, /*1*/ Q : P> {
-    public constructor ClassWithTypePP</*0*/ P, /*1*/ Q : P>()
+public final class ClassWithTypePP</*0*/ P, /*1*/ Q : P!> {
+    public constructor ClassWithTypePP</*0*/ P, /*1*/ Q : P!>()
 }
diff --git a/compiler/testData/loadJava/compiledJava/ClassWithTypePRefNext.txt b/compiler/testData/loadJava/compiledJava/ClassWithTypePRefNext.txt
index e669b40ca24..c9c4b67e5bb 100644
--- a/compiler/testData/loadJava/compiledJava/ClassWithTypePRefNext.txt
+++ b/compiler/testData/loadJava/compiledJava/ClassWithTypePRefNext.txt
@@ -1,5 +1,5 @@
 package test
 
-public open class ClassWithTypePRefNext</*0*/ R : kotlin.Iterable<P>?, /*1*/ P> {
-    public constructor ClassWithTypePRefNext</*0*/ R : kotlin.Iterable<P>?, /*1*/ P>()
+public open class ClassWithTypePRefNext</*0*/ R : kotlin.(Mutable)Iterable<P!>!, /*1*/ P> {
+    public constructor ClassWithTypePRefNext</*0*/ R : kotlin.(Mutable)Iterable<P!>!, /*1*/ P>()
 }
diff --git a/compiler/testData/loadJava/compiledJava/ClassWithTypePRefSelf.txt b/compiler/testData/loadJava/compiledJava/ClassWithTypePRefSelf.txt
index c67b604967c..aea8b50aeaf 100644
--- a/compiler/testData/loadJava/compiledJava/ClassWithTypePRefSelf.txt
+++ b/compiler/testData/loadJava/compiledJava/ClassWithTypePRefSelf.txt
@@ -1,5 +1,5 @@
 package test
 
-public final class ClassWithTypePRefSelf</*0*/ P : kotlin.Enum<P>?> {
-    public constructor ClassWithTypePRefSelf</*0*/ P : kotlin.Enum<P>?>()
+public final class ClassWithTypePRefSelf</*0*/ P : kotlin.Enum<P!>!> {
+    public constructor ClassWithTypePRefSelf</*0*/ P : kotlin.Enum<P!>!>()
 }
diff --git a/compiler/testData/loadJava/compiledJava/ClassWithTypePRefSelfAndClass.txt b/compiler/testData/loadJava/compiledJava/ClassWithTypePRefSelfAndClass.txt
index dbf9c522d2b..7413374c60d 100644
--- a/compiler/testData/loadJava/compiledJava/ClassWithTypePRefSelfAndClass.txt
+++ b/compiler/testData/loadJava/compiledJava/ClassWithTypePRefSelfAndClass.txt
@@ -1,5 +1,5 @@
 package test
 
-public final class ClassWithTypePRefSelfAndClass</*0*/ P : test.ClassWithTypePRefSelfAndClass<P>?> {
-    public constructor ClassWithTypePRefSelfAndClass</*0*/ P : test.ClassWithTypePRefSelfAndClass<P>?>()
+public final class ClassWithTypePRefSelfAndClass</*0*/ P : test.ClassWithTypePRefSelfAndClass<P!>!> {
+    public constructor ClassWithTypePRefSelfAndClass</*0*/ P : test.ClassWithTypePRefSelfAndClass<P!>!>()
 }
diff --git a/compiler/testData/loadJava/compiledJava/FieldOfArrayType.txt b/compiler/testData/loadJava/compiledJava/FieldOfArrayType.txt
index d7cf2d40ff7..567b838a6b3 100644
--- a/compiler/testData/loadJava/compiledJava/FieldOfArrayType.txt
+++ b/compiler/testData/loadJava/compiledJava/FieldOfArrayType.txt
@@ -2,5 +2,5 @@ package test
 
 public open class FieldOfArrayType {
     public constructor FieldOfArrayType()
-    public final var files: kotlin.Array<java.io.File>?
+    public final var files: kotlin.Array<(out) java.io.File!>!
 }
diff --git a/compiler/testData/loadJava/compiledJava/InheritMethodsDifferentReturnTypes.txt b/compiler/testData/loadJava/compiledJava/InheritMethodsDifferentReturnTypes.txt
index da364eee10f..dcdd3a7083d 100644
--- a/compiler/testData/loadJava/compiledJava/InheritMethodsDifferentReturnTypes.txt
+++ b/compiler/testData/loadJava/compiledJava/InheritMethodsDifferentReturnTypes.txt
@@ -4,17 +4,17 @@ public final class InheritMethodsDifferentReturnTypes {
     public constructor InheritMethodsDifferentReturnTypes()
 
     public trait Sub : test.InheritMethodsDifferentReturnTypes.Super1, test.InheritMethodsDifferentReturnTypes.Super2 {
-        public abstract override /*2*/ /*fake_override*/ fun bar(): kotlin.String?
-        public abstract override /*2*/ /*fake_override*/ fun foo(): kotlin.String?
+        public abstract override /*2*/ /*fake_override*/ fun bar(): kotlin.String!
+        public abstract override /*2*/ /*fake_override*/ fun foo(): kotlin.String!
     }
 
     public trait Super1 {
-        public abstract fun bar(): kotlin.String?
-        public abstract fun foo(): kotlin.CharSequence?
+        public abstract fun bar(): kotlin.String!
+        public abstract fun foo(): kotlin.CharSequence!
     }
 
     public trait Super2 {
-        public abstract fun bar(): kotlin.CharSequence?
-        public abstract fun foo(): kotlin.String?
+        public abstract fun bar(): kotlin.CharSequence!
+        public abstract fun foo(): kotlin.String!
     }
 }
diff --git a/compiler/testData/loadJava/compiledJava/InheritMethodsDifferentReturnTypesGeneric.txt b/compiler/testData/loadJava/compiledJava/InheritMethodsDifferentReturnTypesGeneric.txt
index 25c075d6460..b7fa12bb112 100644
--- a/compiler/testData/loadJava/compiledJava/InheritMethodsDifferentReturnTypesGeneric.txt
+++ b/compiler/testData/loadJava/compiledJava/InheritMethodsDifferentReturnTypesGeneric.txt
@@ -3,18 +3,18 @@ package test
 public final class InheritMethodsDifferentReturnTypesGeneric {
     public constructor InheritMethodsDifferentReturnTypesGeneric()
 
-    public trait Sub : test.InheritMethodsDifferentReturnTypesGeneric.Super1<kotlin.String, kotlin.CharSequence>, test.InheritMethodsDifferentReturnTypesGeneric.Super2<kotlin.CharSequence, kotlin.String> {
-        public abstract override /*2*/ /*fake_override*/ fun bar(): kotlin.String?
-        public abstract override /*2*/ /*fake_override*/ fun foo(): kotlin.String?
+    public trait Sub : test.InheritMethodsDifferentReturnTypesGeneric.Super1<kotlin.String!, kotlin.CharSequence!>, test.InheritMethodsDifferentReturnTypesGeneric.Super2<kotlin.CharSequence!, kotlin.String!> {
+        public abstract override /*2*/ /*fake_override*/ fun bar(): kotlin.String!
+        public abstract override /*2*/ /*fake_override*/ fun foo(): kotlin.String!
     }
 
     public trait Super1</*0*/ F, /*1*/ B> {
-        public abstract fun bar(): B?
-        public abstract fun foo(): F?
+        public abstract fun bar(): B!
+        public abstract fun foo(): F!
     }
 
     public trait Super2</*0*/ FF, /*1*/ BB> {
-        public abstract fun bar(): BB?
-        public abstract fun foo(): FF?
+        public abstract fun bar(): BB!
+        public abstract fun foo(): FF!
     }
 }
diff --git a/compiler/testData/loadJava/compiledJava/InnerClassesInGeneric.txt b/compiler/testData/loadJava/compiledJava/InnerClassesInGeneric.txt
index 2f7fcc1e51b..a77fb7f3dc3 100644
--- a/compiler/testData/loadJava/compiledJava/InnerClassesInGeneric.txt
+++ b/compiler/testData/loadJava/compiledJava/InnerClassesInGeneric.txt
@@ -9,6 +9,6 @@ public open class InnerClassesInGeneric</*0*/ P, /*1*/ Q> {
 
     public open inner class Inner2 : test.InnerClassesInGeneric.Inner {
         public constructor Inner2()
-        public open fun iterator(): kotlin.MutableIterator<P>?
+        public open fun iterator(): kotlin.(Mutable)Iterator<P!>!
     }
 }
diff --git a/compiler/testData/loadJava/compiledJava/MethodReferencesOuterClassTP.txt b/compiler/testData/loadJava/compiledJava/MethodReferencesOuterClassTP.txt
index 24fe42c95d0..9da1146ef5f 100644
--- a/compiler/testData/loadJava/compiledJava/MethodReferencesOuterClassTP.txt
+++ b/compiler/testData/loadJava/compiledJava/MethodReferencesOuterClassTP.txt
@@ -5,6 +5,6 @@ public final class MethodReferencesOuterClassTP</*0*/ P> {
 
     public final inner class Inner {
         public constructor Inner()
-        public final fun </*0*/ Q : P> f(): kotlin.Unit
+        public final fun </*0*/ Q : P!> f(): kotlin.Unit
     }
 }
diff --git a/compiler/testData/loadJava/compiledJava/MethodTypePOneUpperBound.txt b/compiler/testData/loadJava/compiledJava/MethodTypePOneUpperBound.txt
index e60e910fb46..8ae76aa6322 100644
--- a/compiler/testData/loadJava/compiledJava/MethodTypePOneUpperBound.txt
+++ b/compiler/testData/loadJava/compiledJava/MethodTypePOneUpperBound.txt
@@ -2,5 +2,5 @@ package test
 
 public open class MethodTypePOneUpperBound {
     public constructor MethodTypePOneUpperBound()
-    public open fun </*0*/ T : kotlin.Cloneable?> bar(): kotlin.Unit
+    public open fun </*0*/ T : kotlin.Cloneable!> bar(): kotlin.Unit
 }
diff --git a/compiler/testData/loadJava/compiledJava/MethodTypePTwoUpperBounds.txt b/compiler/testData/loadJava/compiledJava/MethodTypePTwoUpperBounds.txt
index f17d46f2b20..cb0b79383e7 100644
--- a/compiler/testData/loadJava/compiledJava/MethodTypePTwoUpperBounds.txt
+++ b/compiler/testData/loadJava/compiledJava/MethodTypePTwoUpperBounds.txt
@@ -2,5 +2,5 @@ package test
 
 public open class MethodTypePTwoUpperBounds {
     public constructor MethodTypePTwoUpperBounds()
-    public open fun </*0*/ T : kotlin.Cloneable?> foo(): kotlin.Unit where T : java.lang.Runnable?
+    public open fun </*0*/ T : kotlin.Cloneable!> foo(): kotlin.Unit where T : java.lang.Runnable!
 }
diff --git a/compiler/testData/loadJava/compiledJava/MethodWithTypePP.txt b/compiler/testData/loadJava/compiledJava/MethodWithTypePP.txt
index 043d7ad44f5..3384c76e783 100644
--- a/compiler/testData/loadJava/compiledJava/MethodWithTypePP.txt
+++ b/compiler/testData/loadJava/compiledJava/MethodWithTypePP.txt
@@ -2,5 +2,5 @@ package test
 
 public final class MethodWithTypePP {
     public constructor MethodWithTypePP()
-    public final fun </*0*/ P, /*1*/ Q : P> f(): kotlin.Unit
+    public final fun </*0*/ P, /*1*/ Q : P!> f(): kotlin.Unit
 }
diff --git a/compiler/testData/loadJava/compiledJava/MethodWithTypePRefClassP.txt b/compiler/testData/loadJava/compiledJava/MethodWithTypePRefClassP.txt
index a1f6e8b1888..3b0e3580d34 100644
--- a/compiler/testData/loadJava/compiledJava/MethodWithTypePRefClassP.txt
+++ b/compiler/testData/loadJava/compiledJava/MethodWithTypePRefClassP.txt
@@ -2,5 +2,5 @@ package test
 
 public open class MethodWithTypePRefClassP</*0*/ P> {
     public constructor MethodWithTypePRefClassP</*0*/ P>()
-    public final fun </*0*/ Q : P> f(): kotlin.Unit
+    public final fun </*0*/ Q : P!> f(): kotlin.Unit
 }
diff --git a/compiler/testData/loadJava/compiledJava/MethosWithPRefTP.txt b/compiler/testData/loadJava/compiledJava/MethosWithPRefTP.txt
index 54e29bd7bc1..83de328230d 100644
--- a/compiler/testData/loadJava/compiledJava/MethosWithPRefTP.txt
+++ b/compiler/testData/loadJava/compiledJava/MethosWithPRefTP.txt
@@ -2,5 +2,5 @@ package test
 
 public final class MethosWithPRefTP {
     public constructor MethosWithPRefTP()
-    public final fun </*0*/ P> f(/*0*/ p0: P?): kotlin.Unit
+    public final fun </*0*/ P> f(/*0*/ p0: P!): kotlin.Unit
 }
diff --git a/compiler/testData/loadJava/compiledJava/MyException.txt b/compiler/testData/loadJava/compiledJava/MyException.txt
index 2eda281a3e4..67182826192 100644
--- a/compiler/testData/loadJava/compiledJava/MyException.txt
+++ b/compiler/testData/loadJava/compiledJava/MyException.txt
@@ -1,5 +1,5 @@
 package test
 
 public open class MyException {
-    public constructor MyException(/*0*/ p0: kotlin.String?, /*1*/ p1: kotlin.Throwable?)
+    public constructor MyException(/*0*/ p0: kotlin.String!, /*1*/ p1: kotlin.Throwable!)
 }
diff --git a/compiler/testData/loadJava/compiledJava/RawTypeWithUpperBound.txt b/compiler/testData/loadJava/compiledJava/RawTypeWithUpperBound.txt
index acd5cc51586..4d9ac57ad7f 100644
--- a/compiler/testData/loadJava/compiledJava/RawTypeWithUpperBound.txt
+++ b/compiler/testData/loadJava/compiledJava/RawTypeWithUpperBound.txt
@@ -3,12 +3,12 @@ package test
 public trait RawTypeWithUpperBound {
     
     public trait Bar {
-        public abstract fun f(/*0*/ p0: test.RawTypeWithUpperBound.Foo<out kotlin.CharSequence?>?): kotlin.Unit
+        public abstract fun f(/*0*/ p0: test.RawTypeWithUpperBound.Foo<out kotlin.CharSequence!>!): kotlin.Unit
     }
-    
-    public trait Foo</*0*/ T : kotlin.CharSequence?> {
+
+    public trait Foo</*0*/ T : kotlin.CharSequence!> {
     }
     
     // Static members
-    public final /*synthesized*/ fun Bar(/*0*/ function: (test.RawTypeWithUpperBound.Foo<out kotlin.CharSequence?>?) -> kotlin.Unit): test.RawTypeWithUpperBound.Bar
+    public /*synthesized*/ fun Bar(/*0*/ function: (test.RawTypeWithUpperBound.Foo<out kotlin.CharSequence!>!) -> kotlin.Unit): test.RawTypeWithUpperBound.Bar
 }
diff --git a/compiler/testData/loadJava/compiledJava/RemoveRedundantProjectionKind.txt b/compiler/testData/loadJava/compiledJava/RemoveRedundantProjectionKind.txt
index 781405bde80..dc7ef424f95 100644
--- a/compiler/testData/loadJava/compiledJava/RemoveRedundantProjectionKind.txt
+++ b/compiler/testData/loadJava/compiledJava/RemoveRedundantProjectionKind.txt
@@ -1,6 +1,6 @@
 package test
 
 public trait RemoveRedundantProjectionKind {
-    public abstract fun f(/*0*/ p0: kotlin.Collection<kotlin.CharSequence?>?): kotlin.Unit
-    public abstract fun f(/*0*/ p0: kotlin.Comparable<kotlin.CharSequence?>?): kotlin.Unit
+    public abstract fun f(/*0*/ p0: (kotlin.MutableCollection<out kotlin.CharSequence!>..kotlin.Collection<kotlin.CharSequence!>?)): kotlin.Unit
+    public abstract fun f(/*0*/ p0: kotlin.Comparable<kotlin.CharSequence!>!): kotlin.Unit
 }
diff --git a/compiler/testData/loadJava/compiledJava/UnboundWildcard.txt b/compiler/testData/loadJava/compiledJava/UnboundWildcard.txt
index 78e27a08e43..94bd6583d3d 100644
--- a/compiler/testData/loadJava/compiledJava/UnboundWildcard.txt
+++ b/compiler/testData/loadJava/compiledJava/UnboundWildcard.txt
@@ -2,8 +2,8 @@ package test
 
 public final class UnboundWildcard {
     public constructor UnboundWildcard()
-    public final fun foo(): test.UnboundWildcard.MyClass<out kotlin.CharSequence?>?
+    public final fun foo(): test.UnboundWildcard.MyClass<out kotlin.CharSequence!>!
 
-    public trait MyClass</*0*/ T : kotlin.CharSequence?> {
+    public trait MyClass</*0*/ T : kotlin.CharSequence!> {
     }
 }
diff --git a/compiler/testData/loadJava/compiledJava/constructor/ConstructorGenericDeep.txt b/compiler/testData/loadJava/compiledJava/constructor/ConstructorGenericDeep.txt
index 69ed3a980f8..f5b0442f9dd 100644
--- a/compiler/testData/loadJava/compiledJava/constructor/ConstructorGenericDeep.txt
+++ b/compiler/testData/loadJava/compiledJava/constructor/ConstructorGenericDeep.txt
@@ -1,5 +1,5 @@
 package test
 
 public open class ConstructorGenericDeep {
-    public constructor ConstructorGenericDeep(/*0*/ p0: java.lang.Class<kotlin.Any?>?)
+    public constructor ConstructorGenericDeep(/*0*/ p0: java.lang.Class<kotlin.Any!>!)
 }
diff --git a/compiler/testData/loadJava/compiledJava/constructor/ConstructorGenericSimple.txt b/compiler/testData/loadJava/compiledJava/constructor/ConstructorGenericSimple.txt
index 23fc47a52db..11b091671b0 100644
--- a/compiler/testData/loadJava/compiledJava/constructor/ConstructorGenericSimple.txt
+++ b/compiler/testData/loadJava/compiledJava/constructor/ConstructorGenericSimple.txt
@@ -1,5 +1,5 @@
 package test
 
 public open class ConstructorGenericSimple {
-    public constructor ConstructorGenericSimple(/*0*/ p0: kotlin.Any?)
+    public constructor ConstructorGenericSimple(/*0*/ p0: kotlin.Any!)
 }
diff --git a/compiler/testData/loadJava/compiledJava/constructor/ConstructorGenericUpperBound.txt b/compiler/testData/loadJava/compiledJava/constructor/ConstructorGenericUpperBound.txt
index 11b0af66f1b..23ed8d349ce 100644
--- a/compiler/testData/loadJava/compiledJava/constructor/ConstructorGenericUpperBound.txt
+++ b/compiler/testData/loadJava/compiledJava/constructor/ConstructorGenericUpperBound.txt
@@ -1,5 +1,5 @@
 package test
 
 public open class ConstructorGenericUpperBound {
-    public constructor ConstructorGenericUpperBound(/*0*/ p0: java.util.RandomAccess?)
+    public constructor ConstructorGenericUpperBound(/*0*/ p0: java.util.RandomAccess!)
 }
diff --git a/compiler/testData/loadJava/compiledJava/javaBean/DifferentGetterAndSetter.txt b/compiler/testData/loadJava/compiledJava/javaBean/DifferentGetterAndSetter.txt
index e570edbeaf4..c955510bae8 100644
--- a/compiler/testData/loadJava/compiledJava/javaBean/DifferentGetterAndSetter.txt
+++ b/compiler/testData/loadJava/compiledJava/javaBean/DifferentGetterAndSetter.txt
@@ -3,5 +3,5 @@ package test
 public open class DifferentGetterAndSetter {
     public constructor DifferentGetterAndSetter()
     public open fun getSomething(): kotlin.Int
-    public open fun setSomething(/*0*/ p0: kotlin.String?): kotlin.Unit
+    public open fun setSomething(/*0*/ p0: kotlin.String!): kotlin.Unit
 }
diff --git a/compiler/testData/loadJava/compiledJava/javaBean/JavaBeanVal.txt b/compiler/testData/loadJava/compiledJava/javaBean/JavaBeanVal.txt
index 81ec3ce6694..ab21612209b 100644
--- a/compiler/testData/loadJava/compiledJava/javaBean/JavaBeanVal.txt
+++ b/compiler/testData/loadJava/compiledJava/javaBean/JavaBeanVal.txt
@@ -2,5 +2,5 @@ package test
 
 public open class JavaBeanVal {
     public constructor JavaBeanVal()
-    public open fun getColor(): kotlin.String?
+    public open fun getColor(): kotlin.String!
 }
diff --git a/compiler/testData/loadJava/compiledJava/javaBean/JavaBeanVar.txt b/compiler/testData/loadJava/compiledJava/javaBean/JavaBeanVar.txt
index 814c9028cdf..10f4ef5f5d5 100644
--- a/compiler/testData/loadJava/compiledJava/javaBean/JavaBeanVar.txt
+++ b/compiler/testData/loadJava/compiledJava/javaBean/JavaBeanVar.txt
@@ -2,6 +2,6 @@ package test
 
 public open class JavaBeanVar {
     public constructor JavaBeanVar()
-    public open fun getColor(): kotlin.String?
-    public open fun setColor(/*0*/ p0: kotlin.String?): kotlin.Unit
+    public open fun getColor(): kotlin.String!
+    public open fun setColor(/*0*/ p0: kotlin.String!): kotlin.Unit
 }
diff --git a/compiler/testData/loadJava/compiledJava/javaBean/JavaBeanVarOfGenericType.txt b/compiler/testData/loadJava/compiledJava/javaBean/JavaBeanVarOfGenericType.txt
index 9ffd7cb5a7a..72cbd7fe749 100644
--- a/compiler/testData/loadJava/compiledJava/javaBean/JavaBeanVarOfGenericType.txt
+++ b/compiler/testData/loadJava/compiledJava/javaBean/JavaBeanVarOfGenericType.txt
@@ -2,6 +2,6 @@ package test
 
 public open class JavaBeanVarOfGenericType</*0*/ P> {
     public constructor JavaBeanVarOfGenericType</*0*/ P>()
-    public open fun getCharacters(): java.util.ArrayList<P>?
-    public open fun setCharacters(/*0*/ p0: java.util.ArrayList<P>?): kotlin.Unit
+    public open fun getCharacters(): java.util.ArrayList<P!>!
+    public open fun setCharacters(/*0*/ p0: java.util.ArrayList<P!>!): kotlin.Unit
 }
diff --git a/compiler/testData/loadJava/compiledJava/javaBean/TwoSetters.txt b/compiler/testData/loadJava/compiledJava/javaBean/TwoSetters.txt
index b8b2656d434..c71955f412f 100644
--- a/compiler/testData/loadJava/compiledJava/javaBean/TwoSetters.txt
+++ b/compiler/testData/loadJava/compiledJava/javaBean/TwoSetters.txt
@@ -3,5 +3,5 @@ package test
 public open class TwoSetters {
     public constructor TwoSetters()
     public open fun setSize(/*0*/ p0: kotlin.Int): kotlin.Unit
-    public open fun setSize(/*0*/ p0: kotlin.String?): kotlin.Unit
+    public open fun setSize(/*0*/ p0: kotlin.String!): kotlin.Unit
 }
diff --git a/compiler/testData/loadJava/compiledJava/kotlinSignature/PropertySimpleType.txt b/compiler/testData/loadJava/compiledJava/kotlinSignature/PropertySimpleType.txt
index 9d46a26b651..79fae74031c 100644
--- a/compiler/testData/loadJava/compiledJava/kotlinSignature/PropertySimpleType.txt
+++ b/compiler/testData/loadJava/compiledJava/kotlinSignature/PropertySimpleType.txt
@@ -3,5 +3,5 @@ package test
 public open class PropertySimpleType {
     public constructor PropertySimpleType()
     public final var fieldOne: kotlin.String
-    public final var fieldTwo: kotlin.String?
+    public final var fieldTwo: kotlin.String!
 }
diff --git a/compiler/testData/loadJava/compiledJava/kotlinSignature/StarProjection.txt b/compiler/testData/loadJava/compiledJava/kotlinSignature/StarProjection.txt
index bcc24db07f5..b42a62f2000 100644
--- a/compiler/testData/loadJava/compiledJava/kotlinSignature/StarProjection.txt
+++ b/compiler/testData/loadJava/compiledJava/kotlinSignature/StarProjection.txt
@@ -2,8 +2,8 @@ package test
 
 public final class StarProjection {
     public constructor StarProjection()
-    public final fun foo(): test.StarProjection.MyClass<out kotlin.CharSequence?>
+    public final fun foo(): test.StarProjection.MyClass<out kotlin.CharSequence!>
 
-    public trait MyClass</*0*/ T : kotlin.CharSequence?> {
+    public trait MyClass</*0*/ T : kotlin.CharSequence!> {
     }
 }
diff --git a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/ConflictingProjectionKind.txt b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/ConflictingProjectionKind.txt
index ab55ed672e6..04991e9d630 100644
--- a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/ConflictingProjectionKind.txt
+++ b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/ConflictingProjectionKind.txt
@@ -2,5 +2,5 @@ package test
 
 public open class ConflictingProjectionKind {
     public constructor ConflictingProjectionKind()
-    public open fun foo(/*0*/ p0: kotlin.List<kotlin.Number>?): kotlin.Unit
+    public open fun foo(/*0*/ p0: kotlin.(Mutable)List<kotlin.Number!>!): kotlin.Unit
 }
diff --git a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/ExplicitFieldGettersAndSetters.txt b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/ExplicitFieldGettersAndSetters.txt
index b18fd0c8f41..307507b91ad 100644
--- a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/ExplicitFieldGettersAndSetters.txt
+++ b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/ExplicitFieldGettersAndSetters.txt
@@ -2,5 +2,5 @@ package test
 
 public open class ExplicitFieldGettersAndSetters {
     public constructor ExplicitFieldGettersAndSetters()
-    public final var foo: kotlin.String?
+    public final var foo: kotlin.String!
 }
diff --git a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/ExtraUpperBound.txt b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/ExtraUpperBound.txt
index ae09dbde2a8..1738562a3b1 100644
--- a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/ExtraUpperBound.txt
+++ b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/ExtraUpperBound.txt
@@ -2,5 +2,5 @@ package test
 
 public open class ExtraUpperBound {
     public constructor ExtraUpperBound()
-    public open fun </*0*/ A : java.lang.Runnable?> foo(): kotlin.String?
+    public open fun </*0*/ A : java.lang.Runnable!> foo(): kotlin.String!
 }
diff --git a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/MissingUpperBound.txt b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/MissingUpperBound.txt
index 989185d4f9e..d457bbae3ae 100644
--- a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/MissingUpperBound.txt
+++ b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/MissingUpperBound.txt
@@ -2,5 +2,5 @@ package test
 
 public open class MissingUpperBound {
     public constructor MissingUpperBound()
-    public open fun </*0*/ A : java.lang.Runnable?> foo(): kotlin.String? where A : kotlin.Cloneable?
+    public open fun </*0*/ A : java.lang.Runnable!> foo(): kotlin.String! where A : kotlin.Cloneable!
 }
diff --git a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/NoFieldTypeRef.txt b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/NoFieldTypeRef.txt
index b917eefb126..e508522b29b 100644
--- a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/NoFieldTypeRef.txt
+++ b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/NoFieldTypeRef.txt
@@ -2,5 +2,5 @@ package test
 
 public open class NoFieldTypeRef {
     public constructor NoFieldTypeRef()
-    public final var foo: kotlin.String?
+    public final var foo: kotlin.String!
 }
diff --git a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/NotVarargReplacedWithVararg.txt b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/NotVarargReplacedWithVararg.txt
index 58c68108883..484bf2caf43 100644
--- a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/NotVarargReplacedWithVararg.txt
+++ b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/NotVarargReplacedWithVararg.txt
@@ -2,5 +2,5 @@ package test
 
 public open class NotVarargReplacedWithVararg {
     public constructor NotVarargReplacedWithVararg()
-    public open fun foo(/*0*/ p0: kotlin.String?): kotlin.Unit
+    public open fun foo(/*0*/ p0: kotlin.String!): kotlin.Unit
 }
diff --git a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/ReturnTypeMissing.txt b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/ReturnTypeMissing.txt
index 97223540e62..53e99875ff9 100644
--- a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/ReturnTypeMissing.txt
+++ b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/ReturnTypeMissing.txt
@@ -2,5 +2,5 @@ package test
 
 public open class ReturnTypeMissing {
     public constructor ReturnTypeMissing()
-    public open fun foo(/*0*/ p0: kotlin.String?): kotlin.Int
+    public open fun foo(/*0*/ p0: kotlin.String!): kotlin.Int
 }
diff --git a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/SyntaxError.txt b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/SyntaxError.txt
index 7f2ac874c73..19684a70ead 100644
--- a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/SyntaxError.txt
+++ b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/SyntaxError.txt
@@ -2,5 +2,5 @@ package test
 
 public open class SyntaxError {
     public constructor SyntaxError()
-    public open fun foo(): kotlin.Int?
+    public open fun foo(): kotlin.Int!
 }
diff --git a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/SyntaxErrorInFieldAnnotation.txt b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/SyntaxErrorInFieldAnnotation.txt
index c0c29b3913e..525bb51a098 100644
--- a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/SyntaxErrorInFieldAnnotation.txt
+++ b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/SyntaxErrorInFieldAnnotation.txt
@@ -2,5 +2,5 @@ package test
 
 public open class SyntaxErrorInFieldAnnotation {
     public constructor SyntaxErrorInFieldAnnotation()
-    public final var foo: kotlin.String?
+    public final var foo: kotlin.String!
 }
diff --git a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/VarargReplacedWithNotVararg.txt b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/VarargReplacedWithNotVararg.txt
index 2557fbd3454..eed5132ac74 100644
--- a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/VarargReplacedWithNotVararg.txt
+++ b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/VarargReplacedWithNotVararg.txt
@@ -2,5 +2,5 @@ package test
 
 public open class VarargReplacedWithNotVararg {
     public constructor VarargReplacedWithNotVararg()
-    public open fun foo(/*0*/ vararg p0: kotlin.String? /*kotlin.Array<kotlin.String?>*/): kotlin.Unit
+    public open fun foo(/*0*/ vararg p0: kotlin.String! /*kotlin.Array<(out) kotlin.String!>!*/): kotlin.Unit
 }
diff --git a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongFieldInitializer.txt b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongFieldInitializer.txt
index aa6e3977dfb..0b651101037 100644
--- a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongFieldInitializer.txt
+++ b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongFieldInitializer.txt
@@ -2,5 +2,5 @@ package test
 
 public open class WrongFieldInitializer {
     public constructor WrongFieldInitializer()
-    public final var foo: kotlin.String?
+    public final var foo: kotlin.String!
 }
diff --git a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongFieldMutability.txt b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongFieldMutability.txt
index 6308a3a4534..e724a36fbf2 100644
--- a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongFieldMutability.txt
+++ b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongFieldMutability.txt
@@ -2,6 +2,6 @@ package test
 
 public open class WrongFieldMutability {
     public constructor WrongFieldMutability()
-    public final val fooFinal: kotlin.String? = "Test"
-    public final var fooNotFinal: kotlin.String?
+    public final val fooFinal: kotlin.String! = "Test"
+    public final var fooNotFinal: kotlin.String!
 }
diff --git a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongFieldName.txt b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongFieldName.txt
index da8b62d7dc3..7e090f0f95b 100644
--- a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongFieldName.txt
+++ b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongFieldName.txt
@@ -2,5 +2,5 @@ package test
 
 public open class WrongFieldName {
     public constructor WrongFieldName()
-    public final var foo: kotlin.String?
+    public final var foo: kotlin.String!
 }
diff --git a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongMethodName.txt b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongMethodName.txt
index 8d45d70e303..937fed5961c 100644
--- a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongMethodName.txt
+++ b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongMethodName.txt
@@ -2,5 +2,5 @@ package test
 
 public open class WrongMethodName {
     public constructor WrongMethodName()
-    public open fun foo(): kotlin.String?
+    public open fun foo(): kotlin.String!
 }
diff --git a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongTypeName1.txt b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongTypeName1.txt
index 0089616c8d7..a6cda062bd5 100644
--- a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongTypeName1.txt
+++ b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongTypeName1.txt
@@ -2,5 +2,5 @@ package test
 
 public open class WrongTypeName1 {
     public constructor WrongTypeName1()
-    public open fun foo(/*0*/ p0: kotlin.String?): kotlin.String?
+    public open fun foo(/*0*/ p0: kotlin.String!): kotlin.String!
 }
diff --git a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongTypeName2.txt b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongTypeName2.txt
index d084bb8cc74..ae585048749 100644
--- a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongTypeName2.txt
+++ b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongTypeName2.txt
@@ -2,5 +2,5 @@ package test
 
 public open class WrongTypeName2 {
     public constructor WrongTypeName2()
-    public open fun foo(/*0*/ p0: kotlin.String?): kotlin.String?
+    public open fun foo(/*0*/ p0: kotlin.String!): kotlin.String!
 }
diff --git a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongTypeName3.txt b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongTypeName3.txt
index 10725cca5c3..0df001562cd 100644
--- a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongTypeName3.txt
+++ b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongTypeName3.txt
@@ -2,5 +2,5 @@ package test
 
 public open class WrongTypeName3 {
     public constructor WrongTypeName3()
-    public open fun foo(/*0*/ p0: kotlin.String?): kotlin.String?
+    public open fun foo(/*0*/ p0: kotlin.String!): kotlin.String!
 }
diff --git a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongTypeParameterBoundStructure1.txt b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongTypeParameterBoundStructure1.txt
index 6ebf0f583fa..15f49576d89 100644
--- a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongTypeParameterBoundStructure1.txt
+++ b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongTypeParameterBoundStructure1.txt
@@ -2,5 +2,5 @@ package test
 
 public open class WrongTypeParameterBoundStructure1 {
     public constructor WrongTypeParameterBoundStructure1()
-    public open fun </*0*/ A, /*1*/ B : java.lang.Runnable?> foo(/*0*/ p0: A?, /*1*/ p1: kotlin.List<B>?): kotlin.Unit where B : kotlin.List<kotlin.Cloneable>?
+    public open fun </*0*/ A, /*1*/ B : java.lang.Runnable!> foo(/*0*/ p0: A!, /*1*/ p1: (kotlin.MutableList<out B!>..kotlin.List<B!>?)): kotlin.Unit where B : kotlin.(Mutable)List<kotlin.Cloneable!>!
 }
diff --git a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongTypeParameterBoundStructure2.txt b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongTypeParameterBoundStructure2.txt
index d4b9db26d72..094ec4615af 100644
--- a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongTypeParameterBoundStructure2.txt
+++ b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongTypeParameterBoundStructure2.txt
@@ -2,5 +2,5 @@ package test
 
 public open class WrongTypeParameterBoundStructure2 {
     public constructor WrongTypeParameterBoundStructure2()
-    public open fun </*0*/ A, /*1*/ B : java.lang.Runnable?> foo(/*0*/ p0: A?, /*1*/ p1: kotlin.List<B>?): kotlin.Unit where B : kotlin.List<kotlin.Cloneable>?
+    public open fun </*0*/ A, /*1*/ B : java.lang.Runnable!> foo(/*0*/ p0: A!, /*1*/ p1: (kotlin.MutableList<out B!>..kotlin.List<B!>?)): kotlin.Unit where B : kotlin.(Mutable)List<kotlin.Cloneable!>!
 }
diff --git a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongTypeParametersCount.txt b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongTypeParametersCount.txt
index 43445a9c293..6bbe503b2bf 100644
--- a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongTypeParametersCount.txt
+++ b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongTypeParametersCount.txt
@@ -2,5 +2,5 @@ package test
 
 public open class WrongTypeParametersCount {
     public constructor WrongTypeParametersCount()
-    public open fun </*0*/ A, /*1*/ B> foo(/*0*/ p0: A?, /*1*/ p1: kotlin.List<B>?): kotlin.Unit
+    public open fun </*0*/ A, /*1*/ B> foo(/*0*/ p0: A!, /*1*/ p1: (kotlin.MutableList<out B!>..kotlin.List<B!>?)): kotlin.Unit
 }
diff --git a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongValueParametersCount.txt b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongValueParametersCount.txt
index 9bed085d6be..b4cde051a9c 100644
--- a/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongValueParametersCount.txt
+++ b/compiler/testData/loadJava/compiledJava/kotlinSignature/error/WrongValueParametersCount.txt
@@ -2,5 +2,5 @@ package test
 
 public open class WrongValueParametersCount {
     public constructor WrongValueParametersCount()
-    public open fun foo(): kotlin.Int?
+    public open fun foo(): kotlin.Int!
 }
diff --git a/compiler/testData/loadJava/compiledJava/kotlinSignature/propagation/parameter/NotNullToNullable.txt b/compiler/testData/loadJava/compiledJava/kotlinSignature/propagation/parameter/NotNullToNullable.txt
index c91fe7f5f3c..46e25d17b32 100644
--- a/compiler/testData/loadJava/compiledJava/kotlinSignature/propagation/parameter/NotNullToNullable.txt
+++ b/compiler/testData/loadJava/compiledJava/kotlinSignature/propagation/parameter/NotNullToNullable.txt
@@ -4,11 +4,11 @@ public trait NotNullToNullable {
 
     public trait Sub : test.NotNullToNullable.Super {
         public abstract override /*1*/ /*fake_override*/ fun dummy(): kotlin.Unit
-        public abstract override /*1*/ fun foo(/*0*/ p0: kotlin.String): kotlin.Unit
+        public abstract override /*1*/ fun foo(/*0*/ p0: kotlin.String!): kotlin.Unit
     }
 
     public trait Super {
         public abstract fun dummy(): kotlin.Unit
-        public abstract fun foo(/*0*/ p0: kotlin.String): kotlin.Unit
+        public abstract fun foo(/*0*/ p0: kotlin.String!): kotlin.Unit
     }
 }
diff --git a/compiler/testData/loadJava/compiledJava/kotlinSignature/propagation/parameter/NullableToNotNull.txt b/compiler/testData/loadJava/compiledJava/kotlinSignature/propagation/parameter/NullableToNotNull.txt
index ade5f610b00..488f5a73737 100644
--- a/compiler/testData/loadJava/compiledJava/kotlinSignature/propagation/parameter/NullableToNotNull.txt
+++ b/compiler/testData/loadJava/compiledJava/kotlinSignature/propagation/parameter/NullableToNotNull.txt
@@ -4,11 +4,11 @@ public trait NullableToNotNull {
 
     public trait Sub : test.NullableToNotNull.Super {
         public abstract override /*1*/ /*fake_override*/ fun dummy(): kotlin.Unit
-        public abstract override /*1*/ fun foo(/*0*/ p0: kotlin.String?): kotlin.Unit
+        public abstract override /*1*/ fun foo(/*0*/ p0: kotlin.String!): kotlin.Unit
     }
 
     public trait Super {
         public abstract fun dummy(): kotlin.Unit
-        public abstract fun foo(/*0*/ p0: kotlin.String?): kotlin.Unit
+        public abstract fun foo(/*0*/ p0: kotlin.String!): kotlin.Unit
     }
 }
diff --git a/compiler/testData/loadJava/compiledJava/sam/adapters/SeveralSamParameters.txt b/compiler/testData/loadJava/compiledJava/sam/adapters/SeveralSamParameters.txt
index 1790c483c76..eb138e1c392 100644
--- a/compiler/testData/loadJava/compiledJava/sam/adapters/SeveralSamParameters.txt
+++ b/compiler/testData/loadJava/compiledJava/sam/adapters/SeveralSamParameters.txt
@@ -4,6 +4,6 @@ public open class SeveralSamParameters {
     public constructor SeveralSamParameters()
     
     // Static members
-    public /*synthesized*/ fun findMaxAndInvokeCallback(/*0*/ p0: ((kotlin.String, kotlin.String) -> kotlin.Int)?, /*1*/ p1: kotlin.String?, /*2*/ p2: kotlin.String?, /*3*/ p3: (() -> kotlin.Unit)?): kotlin.String?
+    public /*synthesized*/ fun findMaxAndInvokeCallback(/*0*/ p0: ((kotlin.String!, kotlin.String!) -> kotlin.Int)!, /*1*/ p1: kotlin.String!, /*2*/ p2: kotlin.String!, /*3*/ p3: (() -> kotlin.Unit)!): kotlin.String!
     public open fun findMaxAndInvokeCallback(/*0*/ p0: java.util.Comparator<kotlin.String!>!, /*1*/ p1: kotlin.String!, /*2*/ p2: kotlin.String!, /*3*/ p3: java.lang.Runnable!): kotlin.String!
 }
diff --git a/compiler/testData/loadJava/compiledJava/sam/adapters/TypeParameterOfClass.txt b/compiler/testData/loadJava/compiledJava/sam/adapters/TypeParameterOfClass.txt
index 4792c797fc5..41b399cb364 100644
--- a/compiler/testData/loadJava/compiledJava/sam/adapters/TypeParameterOfClass.txt
+++ b/compiler/testData/loadJava/compiledJava/sam/adapters/TypeParameterOfClass.txt
@@ -2,6 +2,6 @@ package test
 
 public open class TypeParameterOfClass</*0*/ T> {
     public constructor TypeParameterOfClass</*0*/ T>()
-    public final /*synthesized*/ fun foo(/*0*/ p0: ((T, T) -> kotlin.Int)?): kotlin.Unit
+    public final /*synthesized*/ fun foo(/*0*/ p0: ((T!, T!) -> kotlin.Int)!): kotlin.Unit
     public open fun foo(/*0*/ p0: java.util.Comparator<T!>!): kotlin.Unit
 }
diff --git a/compiler/testData/loadJava/compiledJava/sam/adapters/TypeParameterOfMethod.txt b/compiler/testData/loadJava/compiledJava/sam/adapters/TypeParameterOfMethod.txt
index 831ba5eebb9..c5700bab832 100644
--- a/compiler/testData/loadJava/compiledJava/sam/adapters/TypeParameterOfMethod.txt
+++ b/compiler/testData/loadJava/compiledJava/sam/adapters/TypeParameterOfMethod.txt
@@ -4,10 +4,10 @@ public open class TypeParameterOfMethod {
     public constructor TypeParameterOfMethod()
     
     // Static members
-    public /*synthesized*/ fun </*0*/ T> max(/*0*/ p0: ((T, T) -> kotlin.Int)?, /*1*/ p1: T?, /*2*/ p2: T?): T?
+    public /*synthesized*/ fun </*0*/ T> max(/*0*/ p0: ((T!, T!) -> kotlin.Int)!, /*1*/ p1: T!, /*2*/ p2: T!): T!
     public open fun </*0*/ T> max(/*0*/ p0: java.util.Comparator<T!>!, /*1*/ p1: T!, /*2*/ p2: T!): T!
-    public /*synthesized*/ fun </*0*/ T : kotlin.CharSequence?> max2(/*0*/ p0: ((T, T) -> kotlin.Int)?, /*1*/ p1: T?, /*2*/ p2: T?): T?
+    public /*synthesized*/ fun </*0*/ T : kotlin.CharSequence!> max2(/*0*/ p0: ((T!, T!) -> kotlin.Int)!, /*1*/ p1: T!, /*2*/ p2: T!): T!
     public open fun </*0*/ T : kotlin.CharSequence!> max2(/*0*/ p0: java.util.Comparator<T!>!, /*1*/ p1: T!, /*2*/ p2: T!): T!
-    public /*synthesized*/ fun </*0*/ A : kotlin.CharSequence?, /*1*/ B : kotlin.List<A>?> method(/*0*/ p0: ((A, A) -> kotlin.Int)?, /*1*/ p1: B?): kotlin.Unit
+    public /*synthesized*/ fun </*0*/ A : kotlin.CharSequence!, /*1*/ B : kotlin.(Mutable)List<A!>!> method(/*0*/ p0: ((A!, A!) -> kotlin.Int)!, /*1*/ p1: B!): kotlin.Unit
     public open fun </*0*/ A : kotlin.CharSequence!, /*1*/ B : kotlin.(Mutable)List<A!>!> method(/*0*/ p0: java.util.Comparator<A!>!, /*1*/ p1: B!): kotlin.Unit
 }
diff --git a/compiler/testData/loadJava/compiledJava/sam/adapters/TypeParameterOfOuterClass.txt b/compiler/testData/loadJava/compiledJava/sam/adapters/TypeParameterOfOuterClass.txt
index 872f960dac0..2cc5708f804 100644
--- a/compiler/testData/loadJava/compiledJava/sam/adapters/TypeParameterOfOuterClass.txt
+++ b/compiler/testData/loadJava/compiledJava/sam/adapters/TypeParameterOfOuterClass.txt
@@ -5,7 +5,7 @@ public open class TypeParameterOfOuterClass</*0*/ T> {
 
     public open inner class Inner {
         public constructor Inner()
-        public final /*synthesized*/ fun foo(/*0*/ p0: ((T, T) -> kotlin.Int)?): kotlin.Unit
+        public final /*synthesized*/ fun foo(/*0*/ p0: ((T!, T!) -> kotlin.Int)!): kotlin.Unit
         public open fun foo(/*0*/ p0: java.util.Comparator<T!>!): kotlin.Unit
     }
 }
diff --git a/compiler/testData/loadJava/compiledJava/sam/adapters/inheritance/InheritedSameAdaptersWithSubstitution.txt b/compiler/testData/loadJava/compiledJava/sam/adapters/inheritance/InheritedSameAdaptersWithSubstitution.txt
index f4e30d5a396..fc889678c52 100644
--- a/compiler/testData/loadJava/compiledJava/sam/adapters/inheritance/InheritedSameAdaptersWithSubstitution.txt
+++ b/compiler/testData/loadJava/compiledJava/sam/adapters/inheritance/InheritedSameAdaptersWithSubstitution.txt
@@ -3,28 +3,28 @@ package test
 public trait InheritedSameAdaptersWithSubstitution {
     
     public trait Sub : test.InheritedSameAdaptersWithSubstitution.Super1, test.InheritedSameAdaptersWithSubstitution.Super2Substituted {
-        public final override /*2*/ /*fake_override*/ fun foo(/*0*/ p0: ((kotlin.String, kotlin.String) -> kotlin.Int)?): kotlin.Unit
-        public abstract override /*2*/ /*fake_override*/ fun foo(/*0*/ p0: java.util.Comparator<kotlin.String>?): kotlin.Unit
+        public final override /*2*/ /*fake_override*/ fun foo(/*0*/ p0: ((kotlin.String!, kotlin.String!) -> kotlin.Int)!): kotlin.Unit
+        public abstract override /*2*/ /*fake_override*/ fun foo(/*0*/ p0: java.util.Comparator<kotlin.String!>!): kotlin.Unit
     }
     
     public trait Super1 {
-        public final /*synthesized*/ fun foo(/*0*/ p0: ((kotlin.String, kotlin.String) -> kotlin.Int)?): kotlin.Unit
-        public abstract fun foo(/*0*/ p0: java.util.Comparator<kotlin.String>?): kotlin.Unit
+        public final /*synthesized*/ fun foo(/*0*/ p0: ((kotlin.String!, kotlin.String!) -> kotlin.Int)!): kotlin.Unit
+        public abstract fun foo(/*0*/ p0: java.util.Comparator<kotlin.String!>!): kotlin.Unit
     }
     
     public trait Super2</*0*/ T> {
-        public final /*synthesized*/ fun foo(/*0*/ p0: ((T, T) -> kotlin.Int)?): kotlin.Unit
-        public abstract fun foo(/*0*/ p0: java.util.Comparator<T>?): kotlin.Unit
+        public final /*synthesized*/ fun foo(/*0*/ p0: ((T!, T!) -> kotlin.Int)!): kotlin.Unit
+        public abstract fun foo(/*0*/ p0: java.util.Comparator<T!>!): kotlin.Unit
     }
-    
-    public trait Super2Substituted : test.InheritedSameAdaptersWithSubstitution.Super2<kotlin.String> {
-        public final override /*1*/ /*fake_override*/ fun foo(/*0*/ p0: ((kotlin.String, kotlin.String) -> kotlin.Int)?): kotlin.Unit
-        public abstract override /*1*/ /*fake_override*/ fun foo(/*0*/ p0: java.util.Comparator<kotlin.String>?): kotlin.Unit
+
+    public trait Super2Substituted : test.InheritedSameAdaptersWithSubstitution.Super2<kotlin.String!> {
+        public final override /*1*/ /*fake_override*/ fun foo(/*0*/ p0: ((kotlin.String!, kotlin.String!) -> kotlin.Int)!): kotlin.Unit
+        public abstract override /*1*/ /*fake_override*/ fun foo(/*0*/ p0: java.util.Comparator<kotlin.String!>!): kotlin.Unit
     }
     
     // Static members
-    public final /*synthesized*/ fun Sub(/*0*/ function: (java.util.Comparator<kotlin.String>?) -> kotlin.Unit): test.InheritedSameAdaptersWithSubstitution.Sub
-    public final /*synthesized*/ fun Super1(/*0*/ function: (java.util.Comparator<kotlin.String>?) -> kotlin.Unit): test.InheritedSameAdaptersWithSubstitution.Super1
-    public final /*synthesized*/ fun </*0*/ T> Super2(/*0*/ function: (java.util.Comparator<T>?) -> kotlin.Unit): test.InheritedSameAdaptersWithSubstitution.Super2<T>
-    public final /*synthesized*/ fun Super2Substituted(/*0*/ function: (java.util.Comparator<kotlin.String>?) -> kotlin.Unit): test.InheritedSameAdaptersWithSubstitution.Super2Substituted
+    public /*synthesized*/ fun Sub(/*0*/ function: (java.util.Comparator<kotlin.String!>!) -> kotlin.Unit): test.InheritedSameAdaptersWithSubstitution.Sub
+    public /*synthesized*/ fun Super1(/*0*/ function: (java.util.Comparator<kotlin.String!>!) -> kotlin.Unit): test.InheritedSameAdaptersWithSubstitution.Super1
+    public /*synthesized*/ fun </*0*/ T> Super2(/*0*/ function: (java.util.Comparator<T!>!) -> kotlin.Unit): test.InheritedSameAdaptersWithSubstitution.Super2<T>
+    public /*synthesized*/ fun Super2Substituted(/*0*/ function: (java.util.Comparator<kotlin.String!>!) -> kotlin.Unit): test.InheritedSameAdaptersWithSubstitution.Super2Substituted
 }
diff --git a/core/descriptor.loader.java/src/org/jetbrains/jet/lang/resolve/java/lazy/types/LazyJavaTypeResolver.kt b/core/descriptor.loader.java/src/org/jetbrains/jet/lang/resolve/java/lazy/types/LazyJavaTypeResolver.kt
index a637f27722a..e3b90dd87ba 100644
--- a/core/descriptor.loader.java/src/org/jetbrains/jet/lang/resolve/java/lazy/types/LazyJavaTypeResolver.kt
+++ b/core/descriptor.loader.java/src/org/jetbrains/jet/lang/resolve/java/lazy/types/LazyJavaTypeResolver.kt
@@ -45,7 +45,7 @@ class LazyJavaTypeResolver(
                 val canonicalText = javaType.getCanonicalText()
                 val jetType = JavaToKotlinClassMap.getInstance().mapPrimitiveKotlinClass(canonicalText)
                 assert(jetType != null, "Primitive type is not found: " + canonicalText)
-                return jetType!!
+                jetType!!
             }
             is JavaClassifierType -> if (PLATFORM_TYPES && attr.allowFlexible && attr.howThisTypeIsUsed != SUPERTYPE)
                                          LazyFlexibleJavaClassifierType(javaType, attr)
@@ -271,7 +271,20 @@ class LazyJavaTypeResolver(
     ) : DelegatingFlexibleType(
             LazyJavaClassifierType(javaType, attr.toFlexible(FLEXIBLE_LOWER_BOUND)),
             LazyJavaClassifierType(javaType, attr.toFlexible(FLEXIBLE_UPPER_BOUND))
-    )
+    ), CustomTypeVariable {
+
+        override val isTypeVariable: Boolean = lowerBound.getConstructor() == upperBound.getConstructor()
+                                                && lowerBound.getConstructor().getDeclarationDescriptor() is TypeParameterDescriptor
+
+        override val typeParameterDescriptor: TypeParameterDescriptor? = if (isTypeVariable) lowerBound.getConstructor().getDeclarationDescriptor() as TypeParameterDescriptor else null
+
+        override fun substitutionResult(replacement: JetType): JetType {
+            return if (replacement.isFlexible()) replacement
+                   else DelegatingFlexibleType(TypeUtils.makeNotNullable(replacement), TypeUtils.makeNullable(replacement))
+        }
+    }
+
+    private class JavaTypeVariable()
 }
 
 trait JavaTypeAttributes {
diff --git a/core/descriptors/src/org/jetbrains/jet/lang/types/CustomTypeVariable.kt b/core/descriptors/src/org/jetbrains/jet/lang/types/CustomTypeVariable.kt
new file mode 100644
index 00000000000..3653fc4ff94
--- /dev/null
+++ b/core/descriptors/src/org/jetbrains/jet/lang/types/CustomTypeVariable.kt
@@ -0,0 +1,35 @@
+/*
+ * Copyright 2010-2014 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jetbrains.jet.lang.types
+
+import org.jetbrains.jet.lang.descriptors.TypeParameterDescriptor
+
+// To facilitate laziness, any JetType implementation may inherit from this trait,
+// even if it turns out that the type an instance represents is not actually a type variable
+// (i.e. it is not derived from a type parameter), see isTypeVariable
+public trait CustomTypeVariable : JetType {
+    val isTypeVariable: Boolean
+
+    // If typeParameterDescriptor != null <=> isTypeVariable == true, this is not a type variable
+    val typeParameterDescriptor: TypeParameterDescriptor?
+
+
+    // Throws an exception when isTypeVariable == false
+    fun substitutionResult(replacement: JetType): JetType
+}
+
+fun JetType.isCustomTypeVariable() = (this as? CustomTypeVariable)?.isTypeVariable ?: false
\ No newline at end of file
diff --git a/core/descriptors/src/org/jetbrains/jet/lang/types/TypeSubstitutor.java b/core/descriptors/src/org/jetbrains/jet/lang/types/TypeSubstitutor.java
index a68baa3a6b1..3cdfc107673 100644
--- a/core/descriptors/src/org/jetbrains/jet/lang/types/TypeSubstitutor.java
+++ b/core/descriptors/src/org/jetbrains/jet/lang/types/TypeSubstitutor.java
@@ -155,7 +155,7 @@ public class TypeSubstitutor {
         // The type is within the substitution range, i.e. T or T?
         JetType type = originalProjection.getType();
         Variance originalProjectionKind = originalProjection.getProjectionKind();
-        if (type instanceof FlexibleType) {
+        if (type instanceof FlexibleType && !TypesPackage.isCustomTypeVariable(type)) {
             FlexibleType flexibleType = (FlexibleType) type;
             TypeProjection substitutedLower =
                     unsafeSubstitute(new TypeProjectionImpl(originalProjectionKind, flexibleType.getLowerBound()), recursionDepth + 1);
@@ -185,10 +185,17 @@ public class TypeSubstitutor {
                     //noinspection ConstantConditions
                     return TypeUtils.makeStarProjection(typeParameter);
                 case NO_CONFLICT:
-                    boolean resultingIsNullable = type.isNullable() || replacement.getType().isNullable();
-                    JetType substitutedType = TypeUtils.makeNullableAsSpecified(replacement.getType(), resultingIsNullable);
-                    Variance resultingProjectionKind = combine(originalProjectionKind, replacement.getProjectionKind());
+                    JetType substitutedType;
+                    if (TypesPackage.isCustomTypeVariable(type)) {
+                        CustomTypeVariable typeVariable = (CustomTypeVariable) type;
+                        substitutedType = typeVariable.substitutionResult(replacement.getType());
+                    }
+                    else {
+                        boolean resultingIsNullable = type.isNullable() || replacement.getType().isNullable();
+                        substitutedType = TypeUtils.makeNullableAsSpecified(replacement.getType(), resultingIsNullable);
+                    }
 
+                    Variance resultingProjectionKind = combine(originalProjectionKind, replacement.getProjectionKind());
                     return new TypeProjectionImpl(resultingProjectionKind, substitutedType);
                 default:
                     throw new IllegalStateException();
diff --git a/core/descriptors/src/org/jetbrains/jet/lang/types/flexibleTypes.kt b/core/descriptors/src/org/jetbrains/jet/lang/types/flexibleTypes.kt
index eaaefebb9c5..1d3b221532a 100644
--- a/core/descriptors/src/org/jetbrains/jet/lang/types/flexibleTypes.kt
+++ b/core/descriptors/src/org/jetbrains/jet/lang/types/flexibleTypes.kt
@@ -30,6 +30,11 @@ public open class DelegatingFlexibleType(
         override val upperBound: JetType
 ) : DelegatingType(), FlexibleType {
 
+    {
+        assert (!lowerBound.isFlexible()) { "Lower bound of a flexible type can not be flexible: $lowerBound" }
+        assert (!upperBound.isFlexible()) { "Upper bound of a flexible type can not be flexible: $upperBound" }
+    }
+
     override fun getDelegate() = lowerBound
 
     override fun toString() = "('$lowerBound'..'$upperBound')"