code: void zApplyMinimumSpinnerButtonWidthInPixels() {
          if (parent == null) {
              return;
          }
          Dimension decreaseButtonPreferredSize = parent.getComponentDecreaseSpinnerButton().getPreferredSize();
          Dimension increaseButtonPreferredSize = parent.getComponentIncreaseSpinnerButton().getPreferredSize();
          int width = Math.max(decreaseButtonPreferredSize.width, increaseButtonPreferredSize.width);
          int height = Math.max(decreaseButtonPreferredSize.height, increaseButtonPreferredSize.height);
          int minimumWidth = minimumSpinnerButtonWidthInPixels;
          width = (width < minimumWidth) ? minimumWidth : width;
          Dimension newSize = new Dimension(width, height);
          parent.getComponentDecreaseSpinnerButton().setPreferredSize(newSize);
          parent.getComponentIncreaseSpinnerButton().setPreferredSize(newSize);
      }
docs: zApplyMinimumSpinnerButtonWidthInPixels, The applies the specified setting to the time
  picker.