utl_http.begin_request raising ora-29261 Bad Argument when called from within workflow

Our environment is DB 10.2.0.4, APPS 11.5.10.2

We are setting up some new order fraud logic that involves making an http call but we are receiving the following  error when calling utl_http.begin_request from within workflow.

ORA-29273: HTTP request failed

ORA-06512: at "SYS.UTL_HTTP", line 1029

ORA-29261: bad argument

I have traced the failure specifically to the utl_http.begin_request call.  I have attached a simplified procedure that I used to test this call with that simply opens and retrieves the html at http://www.psoug.org.  My actual call is more complex, sending xml data in a  clob and receiving an xml response in a clob but I pared it down to this simple example (which fails in the same place as the more complex example) to isolate the source of the issue and make it easier to troubleshoot.