@Override
    public String toString() {
        return "RefDataValueProxy{" +
                "key='" + key + '\'' +
                ", mapDefinition=" + mapDefinition +
                '}';
    }
If a reference data entry exists for this {@link SingleRefDataValueProxy} pass its value to the consumer
as a {@link TypedByteBuffer}.

@param typedByteBufferConsumer
@return True if the entry is found and the consumer is called.
stroom-pipeline/src/main/java/stroom/pipeline/refdata/store/SingleRefDataValueProxy.java