Kabir, this thing seems a bit fragile. IIUC this was deviced primarily to address the issue with map operations not being transformable, but org.jboss.as.subsystem.test.TransformerAttachmentGrabber doesn't work with map operations, the attachment is always null.

I think the problem is with the step order, in org.jboss.as.subsystem.test.TransformerAttachmentGrabber#execute because the real op being a map operation which does attach(...) happens after the attachment is grabbed, that map ops are runtime only org.jboss.as.controller.operations.global.MapOperations#MAP_CLEAR_DEFINITION