static ByteStreamMessage of(Publisher<? extends HttpData> publisher) {
        requireNonNull(publisher, "publisher");
        if (publisher instanceof ByteStreamMessage) {
            return (ByteStreamMessage) publisher;
        } else {
            return new DefaultByteStreamMessage(StreamMessage.of(publisher));
        }
    }
Creates a new {@link ByteStreamMessage} from the specified {@link Publisher}.
core/src/main/java/com/linecorp/armeria/common/stream/ByteStreamMessage.java