code: public void addAuxHandler(Object handler, String prefix) {
          if (handler == null) {
              throw new NullPointerException();
          }
          auxHandlers.put(prefix, handler);
          allHandlers.add(handler);
  
          addDeclaredMethods(handler, prefix);
          inputConverter.addDeclaredConverters(handler);
          outputConverter.addDeclaredConverters(handler);
  
          if (handler instanceof ShellDependent) {
              ((ShellDependent)handler).cliSetShell(this);
          }
      }
docs: This method is very similar to addMainHandler, except ShellFactory
  will pass all handlers registered with this method to all this shell's subshells.
  
  @see org.gearvrf.debug.cli.Shell#addMainHandler(java.lang.Object, java.lang.String)
  
  @param handler Object which should be registered as handler.
  @param prefix Prefix that should be prepended to all handler's command names.