servlet: tomcat does not support trailer only

[hypnoce]

gRPC version: 1.53.0 gRPC server transport: servlet gRPC client transport: netty

What is your environment?

MacOS 12.4 jdk11

What did you expect to see?

This is a known behaviour where tomcat sends an empty data frame with a end_stream flag instead of a trailer only frame with end_stream flag. While it is a valid http2 behaviour, this is not supported by gRPC who expected end_stream frames to be sent in trailer or trailer-only frame.

What did you see instead?

Internal status error because a data frame is end_stream

Steps to reproduce the bug

The transport tests earlyServerClose_noServerHeaders, earlyServerClose_serverFailure and earlyServerClose_serverFailure_withClientCancelOnListenerClosed reproduce the problem