docs: public void printZ(Appendable out)
          throws IOException
      {
          switch (_precision)
          {
              case YEAR:
              case MONTH:
              case DAY:
              {
                  assert _offset == UNKNOWN_OFFSET;
                  // No need to adjust offset, we won't be using it.
                  print(out);
                  break;
              }
              case MINUTE:
              case SECOND:
              case FRACTION:
              {
                  Timestamp ztime = this.clone();
                  ztime._offset = UTC_OFFSET;
                  ztime.print(out);
                  break;
              }
          }
      }