code: private void checkKeyVisibilityConvention(Node key, Node parent) {
      JSDocInfo info = key.getJSDocInfo();
      if (info == null) {
        return;
      }
      if (!isPrivateByConvention(key.getString())) {
        return;
      }
      Node assign = parent.getParent();
      if (assign == null || !assign.isAssign()) {
        return;
      }
      Node left = assign.getFirstChild();
      if (!left.isGetProp()
          || !left.getLastChild().getString().equals("prototype")) {
        return;
      }
      Visibility declaredVisibility = info.getVisibility();
      // Visibility is declared to be something other than private.
      if (declaredVisibility != Visibility.INHERITED
          && declaredVisibility != Visibility.PRIVATE) {
        compiler.report(JSError.make(key, CONVENTION_MISMATCH));
      }
    }
docs: Determines whether the given OBJECTLIT property visibility violates the coding convention.
  
  @param key The objectlit key node (STRING_KEY, GETTER_DEF, SETTER_DEF, MEMBER_FUNCTION_DEF).