protected Retriever getRetriever()
    {
        if (retriever == null)
        {
            synchronized (Lock.CREATE_RETRIEVER)
            {
                if (retriever == null)
                {
                    retriever = createRetriever();
                }
            }
        }

        return retriever;
    }
protected Retriever getRetriever ( ) { if ( retriever == null ) { synchronized ( Lock . CREATE_RETRIEVER ) { if ( retriever == null ) { retriever = createRetriever ( ) ; } } } return retriever ; }
Get the {@link Retriever} instance used internally to fetch values using an
{@link Evaluator}.

@see #createRetriever()
@see Evaluator

@return the retriever instance