New J2K: separate nullability inference from common one & nullability bug fixes

It will be needed for structure mutability inference

#KT-21467 fixed
#KT-32609 fixed
#KT-32572 fixed
#KT-24677 fixed

nj2k/testData/copyPastePlainText/AsExpression.expected.kt

@@ -3,5 +3,5 @@ import java.util.ArrayList
 
 
 fun foo() {
-    bar(ArrayList<String>())
+    bar(ArrayList<String?>())
 }

nj2k/testData/copyPastePlainText/AsExpressionBody.expected.kt

@@ -2,4 +2,4 @@
 import java.util.ArrayList
 
 
-fun foo() = ArrayList<String>()
+fun foo() = ArrayList<String?>()

nj2k/testData/copyPastePlainText/ImportFromTarget.expected.kt

@@ -4,7 +4,7 @@ import java.util.UUID
 
 
 class ExampleClass {
-    override fun toString(): String {
+    override fun toString(): String? {
         return UUID.randomUUID().toString()
     }
 }

nj2k/testData/copyPastePlainText/ImportResolve.expected.kt

@@ -9,7 +9,7 @@ import java.util.HashMap
 class Target {
     var listOfPlatformType: List<String> = ArrayList()
 
-    var unresolved: UnresolvedInterface<UnresolvedGeneric?>? = UnresolvedImplementation() // Should not add import
+    var unresolved: UnresolvedInterface<UnresolvedGeneric?> = UnresolvedImplementation() // Should not add import
 
 
     var hashMapOfNotImported: Map<ToBeImportedJava, ToBeImportedKotlin> = HashMap()
@@ -18,11 +18,11 @@ class Target {
 
     internal fun acceptJavaClass(tbi: ToBeImportedJava?) {}
 
-    var ambiguousKotlin: IAmbiguousKotlin? = AmbiguousKotlin() // Should not add import in case of 2 declarations in Kotlin
+    var ambiguousKotlin: IAmbiguousKotlin = AmbiguousKotlin() // Should not add import in case of 2 declarations in Kotlin
 
-    var ambiguous: IAmbiguous? = Ambiguous() // Should not add import in case of ambiguous declarations in Kotlin and in Java
+    var ambiguous: IAmbiguous = Ambiguous() // Should not add import in case of ambiguous declarations in Kotlin and in Java
 
-    var ambiguousJava: IAmbiguousJava? = AmbiguousJava()  // Should not add import in case of 2 declarations in Java
+    var ambiguousJava: IAmbiguousJava = AmbiguousJava()  // Should not add import in case of 2 declarations in Java
 
 
     internal fun workWithStatics() {

nj2k/testData/copyPastePlainText/KT13529_1.expected.kt

@@ -3,5 +3,5 @@ import java.util.ArrayList
 
 
 fun foo() {
-    bar(/*comment*/ArrayList<String>())
+    bar(/*comment*/ArrayList<String?>())
 }

nj2k/testData/copyPastePlainText/PostProcessing.expected.kt

@@ -6,7 +6,7 @@ import java.util.ArrayList
 
 class JavaClass {
     internal fun foo(file: File?, target: List<String?>?) {
-        val list = ArrayList<String?>()
+        val list = ArrayList<String>()
         if (file != null) {
             list.add(file.name)
         }