null can be assign to array

TheTypeNode.py

@@ -73,6 +73,9 @@ class TypeStruct():
         if right.isArray and self.name in ['java.lang.Object', 'java.lang.Cloneable', 'java.io.Serializable']:
             return True
 
+        if self.isArray and right.name == 'null':
+            return True
+
         return False
 
 # helper: get list of all super class/interface of a ClassInterNode