[Blazor] MapStaticAssets incorrectly re-encodes files when running the published output in the development environment.

[javiercn]

We have a handler that runs in development to detect files that were added after the build step and serve them as static asset endpoints. We also have logic to gzip those files to serve the gzip version. This logic is only ever wired up when the environment is Development.

When someone publishes their app and sets the environment to Development, the handler gets wired up and incorrectly re-encodes some of the already encoded brotli versions of the files.

This can happen when the app runs inside Visual Studio inside a Docker container using the <ContainerDevelopmentMode>Regular</ContainerDevelopmentMode>.

There is a configuration value that can be set to avoid wiring up this behavior that takes precedence over the Development check.

We can do three things:

• Document the flag and tell people to set it in this scenario.
• Update the logic to ensure that brotli files don't get incorrectly re-encoded.
• Update the logic in the SDK to include a flag in the manifest and unconditionally disable the feature during publish.

We don't expect people to do this outside of the docker scenario mentioned above, but we want to make sure we have some resolution for it.

[javiercn]

This was fixed in 9.0