code: public TypeChecker createTypeChecker(CompilationUnit unit) {
  
          TypeChecker typeChecker = super.createTypeChecker(unit);
          CompileListener typeCheckerListener = getTypeCheckerListener();
          if (typeCheckerListener != null) {
              typeChecker.addCompileListener(typeCheckerListener);
          }
  
          return typeChecker;
      }
docs: Overridden to make public