LiveData to hold not observed values to notify UI about these values after appearance of active observers

BufferedLiveData.kt

/**
 * Hold not observed values to notify UI about these values after appearance of active observers
 */
class BufferedLiveData<T> : LiveData<T>() {

    /**
     * Object to synchronize adding values to buffer in #postValue
     */
    private val lock = Any()

    /**
     * Not observed values
     */
    private val buffer = LinkedList<T>()

    override fun setValue(value: T) {
        if (hasActiveObservers()) {
            super.setValue(value)
        } else {
            // Add the value to buffer
            buffer.add(value)
        }
    }

    override fun postValue(value: T) {
        if (hasActiveObservers()) {
            super.postValue(value)
        } else {
            // Add the value to buffer with synchronization
            synchronized(lock) {
                buffer.add(value)
            }
        }
    }

    override fun onActive() {
        val iterator = buffer.iterator()
        // Check if buffer isn't empty and the LiveData has active observers
        while (iterator.hasNext() && hasActiveObservers()) {
            val value = iterator.next()
            // Notify observers about the value
            setValue(value)

            // Remove the observed value from buffer
            iterator.remove()
        }
    }
}