code: public EntityDocument getEntityDocument(String entityId)
  			throws MediaWikiApiErrorException, IOException {
  		return getEntityDocuments(entityId).get(entityId);
  	}
docs: Fetches the documents for the entity of the given string IDs. The result
  is an {@link EntityDocument} or null if the data could not be fetched.
  
  @param entityId
  string IDs (e.g., "P31" or "Q42") of requested entity
  @return retrieved entity document or null
  @throws MediaWikiApiErrorException
  @throws IOException