code: @Deprecated
      public TimeUnitFormat setNumberFormat(NumberFormat format) {
          if (format == this.format) {
              return this;
          }
          if (format == null) {
              if (locale == null) {
                  isReady = false;
                  mf = mf.withLocale(ULocale.getDefault());
              } else {
                  this.format = NumberFormat.getNumberInstance(locale);
                  mf = mf.withNumberFormat(this.format);
              }
          } else {
              this.format = format;
              mf = mf.withNumberFormat(this.format);
          }
          return this;
      }
docs: Set the format used for formatting or parsing. Passing null is equivalent to passing
  {@link NumberFormat#getNumberInstance(ULocale)}.
  @param format   the number formatter.
  @return this, for chaining.
  @deprecated ICU 53 see {@link MeasureFormat}.