With the following preconditions, the Content-Length header is incorrect:

• Request to a Spring-Controller over an additional Blossom dispatcher servlet (configured as described in the Blossom documentation)
• Request is cached by the Magnolia cache module
• Gzip is enabled for this request

The issue seems to be in the method info.magnolia.module.cache.filter.InMemoryCachedEntry#writeContent. The Spring-Controller adds the Content-Length header with the value of the uncompressed length to the HTTPServletResponse. The writeContent method in InMemoryCachedEntry.java sets the correct Content-Length value to the HTTPServletResponse but not to the Header-MultiMap used with the response wrapper and delivered to the browser.

You can see an incorrect Header value in a browser.