code: public boolean recordAbstract() {
      if (!hasAnySingletonTypeTags()
          && !currentInfo.isInterface()
          && !currentInfo.isAbstract()
          && !currentInfo.isFinal()
          && currentInfo.getVisibility() != Visibility.PRIVATE) {
        currentInfo.setAbstract();
        populated = true;
        return true;
      }
      return false;
    }
docs: Records that the {@link JSDocInfo} being built should have its
  {@link JSDocInfo#isAbstract()} flag set to {@code true}.
  
  @return {@code true} if the flag was recorded and {@code false}
  if it was already defined or it was incompatible with the existing flags