log4j-slf4j2-impl does not include log4j-core, is this intentional?

I noticed that log4j-core has different dependency scope in the two slf4j-impl libraries.

Is this by design?

	`log4j-core` `scope`
`log4j-slf4j-impl`	runtime
`log4j-slf4j2-impl`	test

Looks like it was changed with this commit, which references LOG4J2-2975. I don't see anything that mentions why the scope was changed from runtime to test.

Solution

Yes, removing the runtime dependency on log4j-core was intentional, since the log4j-slf4j2-impl module works with any implementation of the Log4j2 API.

Since version 2.17.2 at least two implementations can be used with the SLF4J-to-LOG4J2 bridge: log4j-core and log4j-to-jul (the third implementation maintained by the Log4j2 project, log4j-to-slf4j, can not be used for obvious reasons).

This choice was not undisputed: cf. LOG4J2 3601 for a discussion.