Java to Kotlin converter: more smartness about variables nullability

j2k/tests/testData/ast/nullability/FieldInitializedWithNull.java

@@ -0,0 +1,8 @@
+//file
+class C {
+    private String s = null;
+
+    void foo() {
+        s = "x"
+    }
+}

j2k/tests/testData/ast/nullability/FieldInitializedWithNull.kt

@@ -0,0 +1,7 @@
+class C() {
+    private var s: String? = null
+
+    fun foo() {
+        s = "x"
+    }
+}

j2k/tests/testData/ast/nullability/InitializedWithNull.java

@@ -0,0 +1,8 @@
+//method
+// !specifyLocalVariableTypeByDefault: true
+void foo(boolean b) {
+  String s = null;
+  if (b) {
+      s = "abc"
+  }
+}

j2k/tests/testData/ast/nullability/InitializedWithNull.kt

@@ -0,0 +1,7 @@
+// !specifyLocalVariableTypeByDefault: true
+fun foo(b: Boolean) {
+    val s: String? = null
+    if (b) {
+        s = "abc"
+    }
+}

j2k/tests/testData/ast/nullability/InitializedWithTernaryNull.java

@@ -0,0 +1,5 @@
+//method
+// !specifyLocalVariableTypeByDefault: true
+void foo(boolean b) {
+  String s = (b ? "abc" : null);
+}

j2k/tests/testData/ast/nullability/InitializedWithTernaryNull.kt

@@ -0,0 +1,7 @@
+// !specifyLocalVariableTypeByDefault: true
+fun foo(b: Boolean) {
+    val s: String? = ((if (b)
+        "abc"
+    else
+        null))
+}