src/main/java/com/googlecode/objectify/impl/SimpleQueryImpl.java
@Override
	public QueryKeys<T> keys() {
		QueryImpl<T> q = createQuery();
		q.checkKeysOnlyOk();
		return new QueryKeysImpl<>(q);
	}
@Override
	public QueryKeys<T> keys() {
		QueryImpl<T> q = createQuery();
		q.checkKeysOnlyOk();
		return new QueryKeysImpl<>(q);
	}
/* (non-Javadoc)
@see com.googlecode.objectify.cmd.Query#keys()