RFR: 8245167: Top package in method profiling shows "null" in JMC

[Andrey Petushkov]

Dear All,

please consider the following patch to add missing package information
into JFR backport
https://cr.openjdk.java.net/~apetushkov/8245167/

Originally the package info was omitted due to dependency on jigsaw
functionality and hence it was thought it's not much relevant for jdk8.
However it turns out it's widely used (e.g. by JMC). So it makes sense
to implement it in jdk8-specific way

The author of the code is Aleksei Semenov <asemenov at azul.com>

Verified by JMC and jfr jtreg tests, including the fixed
jdk/jfr/event/runtime/TestClassLoadEvent

Thanks,
Andrey