Java: Add upgrade and downgrade script

Author: IdrissRio

java/downgrades/9f6026c400996c13842974b24f076a486ad1f69c/compilationUnit.ql

@@ -0,0 +1,5 @@
+class CompilationUnit {
+  override predicate isCompactSourceFile() { none() }
+
+  string toString() { none() }
+}