I am working with blend4j and bioblend to interact with galaxy.  In general, the API seems to require the UUID of a dataset/history, etc.  I may be missing something obvious, but I am not finding great ways to obtain this from cheetah substitutions.  For example, I can use ${history.id} or ${output.id} to get the integer ID of that dataset/history.  ${output.uuid} is not recognized.  

I am looking here as a reference:

and would have expected UUID to get exposed in some manner.  Is there a standard way to obtain the UUID?

Thanks,

Ben