ResponseCacheManager Ignores Cache-Control With Multiple Values

[danielshiplett]

Describe the bug

The normal 'Cache-Control' header that is generated in a response by Spring WebMVC when configured to enable default cache controls contains the value "no-cache, no-store, max-age=0, must-revalidate". Spring Cloud Gateway's LocalResponseCache filtering mechanism doesn't check this value correctly and will apply default cache values to the response rather than skipping caching.

It also appears as if when a WebMVC explicitly specifies the max-age in its ResponseEntity, that Spring Cloud Gateway also ignores this value and uses its own.

Sample

I've created a sample repo with an application and Gateway that show this behavior.

https://github.com/danielshiplett/scg-error

I am also creating a PR that will show a possible fix. However, it caused several other tests to fail. This makes me think that either I am on the wrong track, or this was a major oversight that ended leading to invalid tests. Please let me know which.

[spencergibb]

closing in favor of #3432