Decided to document a very easy yet handy policy from OWSM usage and probably one of the most used: oracle/log_policy.
This policy causes the request, response, and fault messages to be sent to a message log and can be attached either from JDeveloper to your services or references or from the OFWM Enterprise Manager for run time attachments.
Do not forget to increase the log level of oracle.wsm.log.model.MessageLog to Trace32 so you can have the messages log.
The log location is [domain-home]/servers/[soa-managed-server]/logs/owsm/msglogging
The log with the name: diagnostic.log