G'day Dale,
Is the REST API generated from CA 2E?
Do you have a sample of the REST API code?
How are you calling the REST API from a CA 2E function?
I have built a Java generator for CA 2E - that is template based - to allow another customer to generate the Java stubs for interfacing via Mulesoft. Maybe that can be adapted for your particular instance.
Regards,
Darryl