diff --git a/j2k/testData/fileOrElement/annotations/jetbrainsNotNullChainExpr.kt b/j2k/testData/fileOrElement/annotations/jetbrainsNotNullChainExpr.kt
index 03f3bad2bc3..e8ebf943b84 100644
--- a/j2k/testData/fileOrElement/annotations/jetbrainsNotNullChainExpr.kt
+++ b/j2k/testData/fileOrElement/annotations/jetbrainsNotNullChainExpr.kt
@@ -12,10 +12,10 @@ internal class Bar {
 }
 
 internal class Test {
-    fun test(barNotNull: Bar, barNullable: Bar?) {
+    fun test(barNotNull: Bar, barNullable: Bar) {
         barNotNull.fooNotNull.execute()
         barNotNull.fooNullable!!.execute()
-        barNullable!!.fooNotNull.execute()
+        barNullable.fooNotNull.execute()
         barNullable.fooNullable!!.execute()
     }
 }
\ No newline at end of file
diff --git a/j2k/testData/fileOrElement/issues/kt-807.kt b/j2k/testData/fileOrElement/issues/kt-807.kt
index 8dc57ec2a2e..e8fbcb29669 100644
--- a/j2k/testData/fileOrElement/issues/kt-807.kt
+++ b/j2k/testData/fileOrElement/issues/kt-807.kt
@@ -1,4 +1,4 @@
-// ERROR: None of the following functions can be called with the arguments supplied:  public constructor FileInputStream(file: File!) defined in java.io.FileInputStream public constructor FileInputStream(fdObj: FileDescriptor!) defined in java.io.FileInputStream public constructor FileInputStream(name: String!) defined in java.io.FileInputStream
+// ERROR: None of the following functions can be called with the arguments supplied:  public constructor FileInputStream(@NotNull file: File!) defined in java.io.FileInputStream public constructor FileInputStream(@NotNull fdObj: FileDescriptor!) defined in java.io.FileInputStream public constructor FileInputStream(@NotNull name: String!) defined in java.io.FileInputStream
 // ERROR: Type mismatch: inferred type is DataInputStream but InputStream! was expected
 // ERROR: Assignments are not expressions, and only expressions are allowed in this context
 // ERROR: Unresolved reference: close
@@ -21,4 +21,4 @@ internal object FileRead {
         }
 
     }
-}
+}
\ No newline at end of file
diff --git a/j2k/testData/fileOrElement/toKotlinClasses/iterableAndIterator.kt b/j2k/testData/fileOrElement/toKotlinClasses/iterableAndIterator.kt
index 921057ecf88..f56cd0560f3 100644
--- a/j2k/testData/fileOrElement/toKotlinClasses/iterableAndIterator.kt
+++ b/j2k/testData/fileOrElement/toKotlinClasses/iterableAndIterator.kt
@@ -1,9 +1,9 @@
-// ERROR: Return type of 'iterator' is not a subtype of the return type of the overridden member 'public abstract operator fun iterator(): Iterator<String> defined in kotlin.collections.Iterable'
-// ERROR: Return type of 'iterator' is not a subtype of the return type of the overridden member 'public abstract operator fun iterator(): Iterator<String> defined in kotlin.collections.Iterable'
+// ERROR: Null can not be a value of a non-null type Iterator<String>
+// ERROR: Null can not be a value of a non-null type Iterator<String>
 package demo
 
 internal class Test : Iterable<String> {
-    override fun iterator(): Iterator<String>? {
+    override fun iterator(): Iterator<String> {
         return null
     }
 
@@ -13,7 +13,7 @@ internal class Test : Iterable<String> {
 }
 
 internal class FullTest : Iterable<String> {
-    override fun iterator(): Iterator<String>? {
+    override fun iterator(): Iterator<String> {
         return null
     }
 
diff --git a/j2k/testData/fileOrElement/toKotlinClasses/iterableAndIterator2.kt b/j2k/testData/fileOrElement/toKotlinClasses/iterableAndIterator2.kt
index e15f8279a43..2987e300533 100644
--- a/j2k/testData/fileOrElement/toKotlinClasses/iterableAndIterator2.kt
+++ b/j2k/testData/fileOrElement/toKotlinClasses/iterableAndIterator2.kt
@@ -1,11 +1,11 @@
-// ERROR: Return type of 'iterator' is not a subtype of the return type of the overridden member 'public abstract operator fun iterator(): Iterator<String> defined in kotlin.collections.Iterable'
-// ERROR: Return type of 'iterator' is not a subtype of the return type of the overridden member 'public abstract operator fun iterator(): Iterator<String> defined in kotlin.collections.Iterable'
+// ERROR: Null can not be a value of a non-null type Iterator<String>
+// ERROR: Null can not be a value of a non-null type Iterator<String>
 package demo
 
 import java.util.*
 
 internal class Test : Iterable<String> {
-    override fun iterator(): Iterator<String>? {
+    override fun iterator(): Iterator<String> {
         return null
     }
 
@@ -15,7 +15,7 @@ internal class Test : Iterable<String> {
 }
 
 internal class FullTest : Iterable<String> {
-    override fun iterator(): Iterator<String>? {
+    override fun iterator(): Iterator<String> {
         return null
     }
 
diff --git a/j2k/testData/fileOrElement/toKotlinClasses/iterableAndIterator3.kt b/j2k/testData/fileOrElement/toKotlinClasses/iterableAndIterator3.kt
index 71ee936671d..0f9ac65ef6e 100644
--- a/j2k/testData/fileOrElement/toKotlinClasses/iterableAndIterator3.kt
+++ b/j2k/testData/fileOrElement/toKotlinClasses/iterableAndIterator3.kt
@@ -1,8 +1,8 @@
-// ERROR: Return type of 'iterator' is not a subtype of the return type of the overridden member 'public abstract operator fun iterator(): Iterator<String> defined in kotlin.collections.Iterable'
+// ERROR: Null can not be a value of a non-null type Iterator<String>
 package demo
 
 internal class Test : Iterable<String> {
-    override fun iterator(): Iterator<String>? {
+    override fun iterator(): Iterator<String> {
         return null
     }