Regression in SpringWeb 6.1.4 causes ContentType to be missing if ShallowEtagHeaderFilter is used and HTTP response is streamed

[j-be]

Affects: \6.1.4

Upgrading from SpringBoot 3.2.2 to 3.2.3 broke some of our APIs. After thorough examination we were able to narrow the issue down to the SpringWeb going from 6.1.3 to 6.1.4.

Further investigation showed, that the issue only appears if ShallowEtagHeaderFilter is enabled and disableContentCaching is called on it, which seems to be happening if the HTTP response is streamed.

I created a minimal reproducer at https://github.com/j-be/spring-web-contentType-issue

[snicoll]

Thanks for the report. I believe this is a duplicate of #32317. Please test against 6.1.5-SNAPSHOT and report back if that doesn't fix the problem.