Multipart - how to disable Content-Length for a part?

Question: How to disable Content-Length header for a part? I need to do this because an API that I’m using does not allow it (and I can’t do anything about it).

I’m sure that the problem is that header, because I’ve tried to upload a file manually using HttpURLConnection and it works great without Content-Length, and it fails immediately when I add it.

I’ve tried to add interceptor to the request (both addInterceptor and addNetworkInterceptor) in order to remove unwanted header. But it is not here (I can see only Content-Disposition). Is there another way to disable it?

Mentioning https://github.com/square/okhttp/issues/2138

[swankjesse]

You’re the only one. You should petition the owner of the server who has this limitation to fix their server so we don’t have to fix our client.

[swankjesse]

@code-n-roll this might get you unstuck:

  /** Returns a request body with no length available. */
  private RequestBody stripLength(RequestBody delegate) {
    return new RequestBody() {
      @Override public @Nullable MediaType contentType() {
        return delegate.contentType();
      }

      @Override public void writeTo(BufferedSink sink) throws IOException {
        delegate.writeTo(sink);
      }
    };
  }

Use it like this:

    RequestBody part = ...
    MultipartBody body = new MultipartBody.Builder("123")
        .addPart(stripLength(part))
        .build();