code: @Override
      public void setNumberFormat(NumberFormat newNumberFormat) {
          // Override this method to update local zero padding number formatter
          super.setNumberFormat(newNumberFormat);
          initLocalZeroPaddingNumberFormat();
          initializeTimeZoneFormat(true);
  
          if (numberFormatters != null) {
              numberFormatters = null;
          }
          if (overrideMap != null) {
              overrideMap = null;
          }
      }
docs: Overrides superclass method and
  This method also clears per field NumberFormat instances
  previously set by {@link #setNumberFormat(String, NumberFormat)}