code: @Override
      public boolean isContainedIn(ImmutableCQ cq1, ImmutableCQ cq2) {
          return cq2.getAnswerVariables().equals(cq1.getAnswerVariables())
                  && !cq2.getAtoms().stream().anyMatch(a -> !cq1.getAtoms().contains(a));
      }
docs: Check if query cq1 is contained in cq2, syntactically. That is, if the
  head of cq1 and cq2 are equal and each atom in cq2 is also in the body of cq1