default InputStream toInputStream(Function<? super T, ? extends HttpData> httpDataConverter,
                                      EventExecutor executor) {
        requireNonNull(httpDataConverter, "httpDataConverter");
        requireNonNull(executor, "executor");
        return new StreamMessageInputStream<>(this, httpDataConverter, executor);
    }
Adapts this {@link StreamMessage} to {@link InputStream}.

@param executor the executor to subscribe
core/src/main/java/com/linecorp/armeria/common/stream/StreamMessage.java