A simple example has been attach that demonstrates an issue using Annotation Based Expression Language to check a value in the method sigature:

The following code is being used:

public boolean returnSuccess (@Simple("${exception} == null") boolean success) {
        return success;
    }

When an exception is set the method still returns true.

The following code demonstrates a work around for this issue:

public boolean returnSuccess(@Simple("${exception}") String exception)
	{		
		return (exception == null ? true : false);
	}