code: public void removeNodeMetaData(Object key) {
          if (key==null) throw new GroovyBugError("Tried to remove meta data with null key "+this+".");
          if (metaDataMap == null) {
              return;
          }
          metaDataMap.remove(key);
      }
docs: Removes a node meta data entry.
  
  @param key - the meta data key
  @throws GroovyBugError if the key is null