I would recommend people to use a persistent collection library like Vavr instead (many other options too).

It provides the same functionality but without string field references (a disaster for refactoring). Additionally it won't require learning a new DSL for basic comparisons because the logic is contained in normal Java code with lambdas and method references.

this:

  Gather query = Gather.where("age").greaterThan(50).and("status").is("active");
  List<Employee> filtered = query.find(employees);
  

becomes this:

  List<Employee> filtered = employess.filter(e -> e.age > 50 && e.status.equals("active"));