Composite.kt

interface Component {
    fun operation()
}

class Leaf : Component {
    override fun operation() {
        // implementation
    }
}

class Composite : Component {
    private val children = mutableListOf<Component>()

    override fun operation() {
        for (child in children) {
            child.operation()
        }
    }

    fun add(component: Component) {
        children.add(component)
    }

    fun remove(component: Component) {
        children.remove(component)
    }
}