Allow Kogito to forward custom transport headers/attributes to external services depending on the transport or message being used (HTTP Rest, CloudEvents, ...)

This will allow processes behave like an orchestrator when required. Some orchestrated services might need to be aware of certain context that is usually defined in HTTP Headers or CloudEvent attributes (or any other transport that is not yet supported in Kogito).

This feature specifically focus the propagation of the LRA context and potentially any tracing context like opentracing.

A possible way of defining how a header should be forwarded can be by adding a property or set of properties to the application properties with the header/attribute names that must be forwarded or with wildcards. e.g.

kogito.transport.forward_attributes.lra=LRA_*

kogito.transport.forward_attributes.custom=MY_CUSTOM_ATTRIBUTE, MY_OTHER_ATTRIBUTE

When creating the process instance (at the process start or signal), depending on the transport used, the matching headers will be added to the process instance metadata and each service handler will add them to the request accordingly.