FunctionProcessor.kt

override fun visitClassDeclaration(classDeclaration: KSClassDeclaration, data: Unit) {
    if (classDeclaration.classKind != ClassKind.INTERFACE) {
        logger.error("Only interface can be annotated with @Function", classDeclaration)
        return
    }

    // Getting the @Function annotation object.
    val annotation: KSAnnotation = classDeclaration.annotations.first {
        it.shortName.asString() == "Function"
    }

    // Getting the 'name' argument object from the @Function.
    val nameArgument: KSValueArgument = annotation.arguments
        .first { arg -> arg.name?.asString() == "name" }

    // Getting the value of the 'name' argument.
    val functionName = nameArgument.value as String
}