code: @Override
      public Map<String, String> getValues() {
          HashMap<String, String> result = new HashMap<>();
  
          if (BeforeDate != null) result.put("BeforeDate", Long.toString(BeforeDate));
          if (AfterDate != null) result.put("AfterDate", Long.toString(AfterDate));
  
          return result;
      }
docs: Gets map of fields and values.
  
  @return Collection of field name-field value pairs.