@Nullable abstract fun receive(): Message<*>
Receive a message from this channel, blocking indefinitely if necessary.
Return
the next available Message or null if interrupted
@Nullable abstract fun receive(timeout: Long): Message<*>
Receive a message from this channel, blocking until either a message is available or the specified timeout period elapses.
timeout - the timeout in milliseconds or MessageChannel#INDEFINITE_TIMEOUT.
Return
the next available Message or null if the specified timeout period elapses or the message reception is interrupted