code: public boolean validateWatcher(String name, Watcher watcher){
          synchronized(watchers){
              if(watchers.containsKey(name)){
                  return watchers.get(name).contains(watcher);
              }
              return false;
          }
      }
docs: Validate whether the Watcher register to the Service.
  
  @param name
  the Service Name.
  @param watcher
  the Watcher Object.
  @return
  return true if the Watcher registered to the Service.