public void detach() {
        if (serverHandler == null) {
            throw new IllegalStateException("No server handler registered");
        }
        detached = true;
    }
Detach a method invocation. This method may only be invoked
during method handling (RPC server aspect). If this method is
invoked, the method is not returned when the method handler
returns. Instead, the application must invoke the {@link
#returnRequest returnRequest} method when it wants the request
to be returned.

@throws IllegalStateException if invoked inappropriately
jrt/src/com/yahoo/jrt/Request.java