@Nullable
    static CollectionCondition parse(Object target, String method, Object[] args, boolean safe) {
      if (safe) return null;

      if (target == SpockRuntime.class) {
        if (SpockRuntime.MATCH_COLLECTIONS_AS_SET.equals(method) || SpockRuntime.MATCH_COLLECTIONS_IN_ANY_ORDER.equals(method)) {
          return new CollectionCondition(method, args[0], args[1]);
        }
      }
      return null;
    }
A condition of the form "foo equalTo(bar)" or "that(foo, equalTo(bar)"
or "expect(foo, equalTo(bar)", where 'equalTo' returns a Hamcrest matcher.
spock-core/src/main/java/org/spockframework/runtime/SpockRuntime.java