public static Specification<PerfTest> idEmptyPredicate() {
		return (Specification<PerfTest>) (root, query, cb) -> root.get("id").isNotNull();
	}
Get the {@link Specification} whichs provide empty predicate.

This is for the base element for "and" or "or" combination.

@return {@link Specification}
ngrinder-controller/src/main/java/org/ngrinder/perftest/repository/PerfTestSpecification.java