code: public final synchronized boolean hasListeners(String name) {
          if (this.map == null) {
              return false;
          }
          L[] array = this.map.get(null);
          return (array != null) || ((name != null) && (null != this.map.get(name)));
      }
docs: Indicates whether the map contains
  at least one listener to be notified.
  
  @param name  the name of the property
  @return      {@code true} if at least one listener exists or
  {@code false} otherwise