I have a method that logs on entry (based on a flag), and I would like
to be able to identify the caller in the trace. Now, I can use
Thread.getStackTrace() to get the static thread stack, from which I
can get the invoking class and method. However, I would like to get
hold of the 'this' object reference of the immediate parent stack
frame, so that I can identify the instance of the caller. Is there a
way to do this? The debugging interface seems written to access a
different JVM, and I can't see a way to put it to use.

This code does not have to be very efficient, as it will only be
turned on rarely in fault isolation. Any help is greatly appreciated.