code: public boolean isSupported(DateTimeFieldType type) {
          if (type == null) {
              return false;
          }
          return type.getField(getChronology()).isSupported();
      }
docs: Checks if the field type specified is supported by this instant and chronology.
  This can be used to avoid exceptions in {@link #get(DateTimeFieldType)}.
  
  @param type  a field type, usually obtained from DateTimeFieldType
  @return true if the field type is supported