CallbackContainer

interface CallbackContainer<T : Any!>

Interface that defines basic operations related to handling callbacks.

addCallback	`abstract fun addCallback(callback: T): Unit` Register callback for updates.
doOnEachCallback	`abstract fun doOnEachCallback(action: Block<T>): Unit` Perform an action on all registered callbacks.
first	`abstract fun first(): Optional<T>`
getAllCallbacks	`abstract fun getAllCallbacks(): MutableList<T>` Get list of currently registered callbacks.
getSize	`abstract fun getSize(): Long`
isEmpty	`abstract fun isEmpty(): Boolean`
last	`abstract fun last(): Optional<T>`
removeAllCallbacks	`abstract fun removeAllCallbacks(): Unit` Remove all registered callbacks.
removeCallback	`abstract fun removeCallback(callback: T): Unit` Remove updates for a specific callback.

open class ListCallbackContainer<T : Any!> : CallbackContainer<T>

Default callback container implementation. It uses ArrayList to store registered callbacks.