add cast: don't unbox for null types (IDEA-193174)

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/addTypeCast/afterNullToPrimitiveType.java

@@ -0,0 +1,8 @@
+// "Cast parameter to 'java.lang.Integer'" "true"
+class a {
+   void m(Integer i){}
+   void m(String s) {}
+   void f() {
+       m((Integer) null);
+   }
+}

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/addTypeCast/beforeNullToPrimitiveType.java

@@ -0,0 +1,8 @@
+// "Cast parameter to 'java.lang.Integer'" "true"
+class a {
+   void m(Integer i){}
+   void m(String s) {}
+   void f() {
+       m(<caret>null);
+   }
+}