@Mule Annotation

A parameter injection annotation that can be used on component entry points and transformer methods, this annotation can be used to execute a Mule Expression on the message payload with the result being passed into the method.

public class MyComponent {
    public Object process(@Mule("message.payload") String payload) {
        // do stuff
    }
}

Mule defines a micro language for accessing the current message and Mule environment, more information can be found here.