code: protected void onValueSelect(String value, boolean fireEvents) {
  
          String oldValue = m_selectedValue;
          selectValue(value);
          if (fireEvents) {
              if ((oldValue == null) || !oldValue.equals(value)) {
                  // fire value change only if the the value really changed
                  ValueChangeEvent.<String> fire(this, value);
              }
          }
      }
docs: Internal handler method which is called when a new value is selected.<p>
  
  @param value the new value
  @param fireEvents true if change events should be fired