code: public Promise waitForServices(long timeoutMillis, Collection<String> services) {
  		return serviceRegistry.waitForServices(timeoutMillis, services);
  	}
docs: Waits for a collection of services. Sample code:<br>
  <br>
  Set&lt;String&gt; serviceNames = ...<br>
  broker.waitForServices(5000, serviceNames).then(in -&gt; {<br>
  broker.getLogger().info("Ok");<br>
  }.catchError(error -&gt; {<br>
  broker.getLogger().info("Failed / timeout");<br>
  }
  
  @param timeoutMillis
  timeout in milliseconds
  @param services
  collection of service names
  
  @return listenable Promise