The custom plugin java library must log in json

The Java custom plugin library performs logging activities using the LOG4J library (http://www.slf4j.org/). A useful reference can be Quarkus, which gives the possibility to configure the log and documents as https://quarkus.io/guides/logging

Start by locating the custom plugin Java library's LOG4J/SLF4J logging setup. Review Quarkus's logging configuration and documentation as a reference, then determine the supported configuration and output expectations. Done means the library emits its logs in JSON format and the configuration is documented.

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