Mark unused parameters in Kotlin

With the @Suppress annotation You can suppress any diagnostics on any declaration or expression.

Examples:
Suppress warning on parameter:

fun foo(a: Int, @Suppress("UNUSED_PARAMETER") b: Int) = a

Suppress all UNUSED_PARAMETER warnings inside declaration

@Suppress("UNUSED_PARAMETER")
fun foo(a: Int,  b: Int) {
  fun bar(c: Int) {}
}

@Suppress("UNUSED_PARAMETER")
class Baz {
    fun foo(a: Int,  b: Int) {
        fun bar(c: Int) {}
    }
}

Additionally IDEA’s intentions(Alt+Enter) can help you to suppress any diagnostics: