ADD ? IN RULE AIDL

Aidl.g4

@@ -5,10 +5,10 @@ grammar Aidl;
 }
 
 aidl: 
-    packageStatement ( 
+    packageStatement? (
         parcelableStatement | 
         importStatement* interfaceStatement
-    );
+    )?;
 
 packageStatement: 
     PACKAGE name SE;