As discovered while analyzing the request from #1143, it became apparent that the current semantic conventions do lack the information about the middleware running on the runtime within the process. Adding this information makes the traces more valuable - the proposed change makes it possible to visualize that Tomcat 9.0.39 application server is sending messages to a Kafka message queue which in turn has a subscriber running on GlassFish 5.0 persisting the content to Druid 0.15.0. In the current form, it seems that the semantic conventions leave this information at the span level, which would be creating redundancy in outbound communication from the agent and/or not capture the information in unified manner, making it harder for Otel-compliant servers to visualize such traces.

Changed the description, removed the hierarchy of process-runtime-middleware, as middleware can be directly running on process as well.

Middleware example now more clearly highlights the value of different attributes. Also rephrased the MUST and SHOULD categories for middleware type and name.