public Bus<M> addObserver(BusObserver<M> observer) {
		if(observer != null) {
			logger.info("adding observer of class '{}'", observer.getClass().getSimpleName());
			observers.add(observer);
		}
		return this;
	}
public Bus < M > addObserver ( BusObserver < M > observer ) { if ( observer != null ) { logger . info ( "adding observer of class '{}'" , observer . getClass ( ) . getSimpleName ( ) ) ; observers . add ( observer ) ; } return this ; }
Adds an observer to this message bus.

@param observer
the observer.
@return
the object itself, for method chaining.