docs: public static DateTimeComparator getInstance(DateTimeFieldType lowerLimit, DateTimeFieldType upperLimit) {
          if (lowerLimit == null && upperLimit == null) {
              return ALL_INSTANCE;
          }
          if (lowerLimit == DateTimeFieldType.dayOfYear() && upperLimit == null) {
              return DATE_INSTANCE;
          }
          if (lowerLimit == null && upperLimit == DateTimeFieldType.dayOfYear()) {
              return TIME_INSTANCE;
          }
          return new DateTimeComparator(lowerLimit, upperLimit);
      }