code: public boolean isSpecNodeInLevelByTargetID(final String targetId) {
          final SpecNode foundTopic = getClosestSpecNodeByTargetId(targetId, false);
          return foundTopic != null;
      }
docs: Checks to see if a SpecNode exists within this level or its children.
  
  @param targetId The Target ID of the level/topic to see if it exists.
  @return True if the level/topic exists within this level or its children otherwise false.