When extending the java agent, is it possible to find all already instrumented packages to filter them out from the type matcher?

[DGuhr]

Hi 👋
So, the use case is basically #2574 - instrument all methods under a package.

I had a conversation in the CNCF slack, and package-level instrumentation is generally possible for sure, but you have to be careful and filter out a lot of already auto-instrumented packages to not accidentally overwrite them.

It'd be awesome if there's an api/ framework method that would allow to, instead, do something around the lines of this example:

ElementMatchers.nameStartsWith(packageName + ".")
                .and(not(alreadyAutoInstrumentedPackages()))

where alreadyAutoInstrumentedPackages checks the currently available auto-instrumentation in the agent and adds it to the list, so makes sure nothing is overwritten.

Maybe there is already a way to achieve this without creating all the filters, so I wanted to ask here first.