// 1) Modify your message to receive the argument (or multiple arguments… just // increase the argument number)….
AIRTEST=Hey {0}, what is up?

//2) Inject the Messages bundle as you probably are already doing…
    @In
    Map<String, String> messages = null;


//3) Use java.text.MessageFormat to perform the parse  (Note:  The Object [] can //receive various datatypes.  For more info lookup MessageFormat)...
MessageFormat.format( messages.get( "AIRTEST" ), new Object[] {"Chuck"} )

Pass Arguments to the Messages Bundle

Java