docs: private boolean convertDateTimeLiteral(Session session, Expression a,
                                             Expression b) {
  
          if (a.dataType.isDateTimeType()) {}
          else if (b.dataType.isDateTimeType()) {
              Expression c = a;
  
              a = b;
              b = c;
          } else {
              return false;
          }
  
          if (a.dataType.isDateTimeTypeWithZone()) {
              return false;
          }
  
          if (b.opType == OpTypes.VALUE && b.dataType.isCharacterType()) {
              b.valueData = a.dataType.castToType(session, b.valueData,
                                                  b.dataType);
              b.dataType = a.dataType;
  
              return true;
          }
  
          return false;
      }