This optional attribute can contain a JMS selector expression used for consuming messages from the source destination. Only messages that match the selector expression will be bridged from the source to the target destination

Please note it is always more performant to apply selectors on source topic subscriptions to source queue consumers.

The selector expression must follow the JMS selector syntax specified here: http://java.sun.com/j2ee/1.4/docs/api/javax/jms/Message.html