I changed my build.gradle to include

compileJava {
	options.compilerArgs << "-Xlint"
	[...]
}

which is generally considered good practice.

 

When trying to compile my mod using gradlew build I get this error:

Quote

warning: No processor claimed any of these annotations: net.minecraftforge.fml.common.Mod.EventHandler,net.minecraftforge.fml.common.eventhandler.SubscribeEvent,net.minecraftforge.fml.common.SidedProxy,net.minecraftforge.fml.common.Mod,
net.minecraftforge.fml.relauncher.SideOnly,javax.annotation.Nonnull,net.minecraftforge.common.capabilities.CapabilityInject,net.minecraftforge.fml.common.Mod.Instance,javax.annotation.Nullabla

What is causing this?

Wouldn't it make sense to declare the annotations somewhere inside Forge code?