find and warn, remove unused public classes, methods by scalafix SyntacticRule.
addSbtPlugin("com.github.xuwei-k" % "unused-code-plugin" % "version")> unusedCode
> scalafix WarnUnusedCode
> scalafix RemoveUnusedCode
build.sbt
import scala.concurrent.duration.*
ThisBuild / unusedCodeConfig ~= { c =>
  c.copy(
    excludeNameRegex = Set(
      ".*Server"
    ),
    excludePath = c.excludePath ++ Set(
      "glob:some-project/**"
    ),
    excludeGitLastCommit = Some(
      365.days
    ),
    excludeMainMethod = false,
    dialect = unused_code.Dialect.Scala3,
  )
}