question: public void consumer ( String path , @ Pin ServiceRefAmp serviceRef , Result < ? super Cancel > result ) { if ( path . isEmpty ( ) ) { result . fail ( new ServiceException ( L . l ( "Invalid event location '{0}'" , path ) ) ) ; return ; } String address = address ( path ) ; EventNodeAsset node = lookupPubSubNode ( address ) ; Cancel cancel = node . consumeImpl ( serviceRef ) ; result . ok ( cancel ) ; }
target:  Consume a callback to a location.