code: public void setIcon(Icon icon) {
          Icon old = null;
          if (iconInfo == CommandButtonIconInfo.BLANK_ICON_INFO) {
              if (icon != null) {
                  // New IconInfo fires event
                  setIconInfo(new CommandButtonIconInfo(icon));
              }
          }
          else {
              old = iconInfo.getIcon();
              this.iconInfo.setIcon(icon);
          }
          firePropertyChange(ICON_PROPERTY, old, icon);
      }
docs: Set the main default icon to be associated with the command.
  
  @param icon The main default icon. May be null.