MIME type issue with Apache mod_jk and mod_proxy serving plain text

Some apps do not properly set mime types of content they serve, but still may work properly when served standalone because client applications like browsers are able to interpret the type of the content.  But when served behind Apache, these apps will not behave correctly because Apache will provide a default type of text/plain.

The solution is to add a DefaultType None line to your apache virtual host for these web apps:

DefaultType None

Here are the docs