code: private static CompareOp reverseCompareOp(CompareOp compareOp) {
      switch (compareOp) {
      case EQUAL:
      case NOT_EQUAL:
      case NO_OP:
        return compareOp;
      case LESS:
        return CompareOp.GREATER;
      case LESS_OR_EQUAL:
        return CompareOp.GREATER_OR_EQUAL;
      case GREATER:
        return CompareOp.LESS;
      case GREATER_OR_EQUAL:
        return CompareOp.LESS_OR_EQUAL;
      default:
        return CompareOp.NO_OP;
      }
    }
docs: For some reason, the ordering of CheckAndMutate operations is the inverse order of normal
  {@link ValueFilter} operations.
  
  @param compareOp
  @return the inverse of compareOp