private void maybeInvokeOnSubscribe(SubscriptionImpl subscription, Subscriber<Object> subscriber) {
        if (invokedOnSubscribe) {
            return;
        }
        invokedOnSubscribe = true;
        subscriber.onSubscribe(subscription);
    }
Creates a new instance.

@deprecated Use {@link StreamMessage#streaming()} instead.
core/src/main/java/com/linecorp/armeria/common/stream/DefaultStreamMessage.java