What is this deprecated Gradle feature, and how do O stop it?

Detecting annotation processors on the compile classpath has been deprecated. Gradle 5.0 will ignore annotation processors on the compile classpath. The following annotation processors were detected on the compile classpath: 'org.apache.logging.log4j.core.config.plugins.processor.PluginProcessor'.

What? OK, let me elaborate: I am working on a Forge mod (as the program is used for) for 1.15.2, and I see the above error. I had two originally, but I just had to fix my workspace filename. But, THAT; I have no clue about it. Anything that might be triggering this warning? (I know it's a warning, but I want this project to be compatible going into 1.17 and beyond.)