Java to Kotlin converter: added heuristics that values of types like Integer are likely nullable

j2k/tests/testData/ast/formatting/nonStaticMembers.kt

@@ -5,7 +5,7 @@ class F() {
 
     fun f2() {
     }
-    var i = 0
+    var i: Int? = 0
 
     fun f3() {
     }

j2k/tests/testData/ast/formatting/nonStaticMembersWithComments.kt

@@ -16,7 +16,7 @@ class F() {
 
     fun f2() {
     }
-    var i = 0
+    var i: Int? = 0
 
     fun f3() {
     }

j2k/tests/testData/ast/formatting/staticAndNonStaticMembersWithComments.kt

@@ -24,7 +24,7 @@ class F() {
 
         fun f1() {
         }
-        var i = 0
+        var i: Int? = 0
 
         //c5
 

j2k/tests/testData/ast/formatting/staticMembersWithComments.kt

@@ -17,7 +17,7 @@ class F() {
 
         fun f2() {
         }
-        var i = 0
+        var i: Int? = 0
 
         fun f3() {
         }