private static <F,T> Evaluator<T> createEvaluator(Path<F> path, Expression<T> projection) {
        return evaluatorFactory.create(EmptyMetadata.DEFAULT,
                Collections.singletonList(path), projection);
    }
Wrap a Querydsl expression into a Guava function

@param projection projection to wrap
@return Guava function
querydsl-collections/src/main/java/com/querydsl/collections/FunctionalHelpers.java