When calling from a FLOW service, simply invoke the Java service as you would any other service.
If you’re trying to call a service from within a Java service, use the one of the doInvoke methods in the Service class defined in the IS Java API.
You should also consider whether or not you really need to be writing a Java service. You may need to write Java, depending on the need, but chances are you probably can write a FLOW service instead of a Java service.
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