ClSample

//ClientProxy class
public class ClientProxy extends CommonProxy
{
  //Register in main method via calling "proxy.registerKeyBindings"
  @Override
  public void registerKeyBindings(){
  FMLCommonHandler.instance().bus().register(new KeyHandler());
  }
}

//CommonProxy class
public class CommonProxy
{
  public void registerKeyBindings(){
  //leave empty
  }
}