Guise Mummy supports a "content file", a resource stand-in for the content of a collection. Put another way, if one browses to foo/bar/, this file contains the content that will be shown.
Traditionally this has been an index.html file, such as foo/bar/index.html. Traditionally, instead of simply showing the content, the web server would redirect to the file. But the modern approach is simply to show the content of foo/bar/index.html when browsing to foo/bar/. With this approach foo/bar/index.html becomes an implementation detail, and in fact Guise Mummy hides it altogether from browsing.
The first versions of Guise Mummy hard-coded the name index.xhtml as the expected content file. Besides being inflexible, this causes problems with the support of HTML files in GUISE-111: if an index.html file is present, it isn't recognized as the content file, and a phantom index.xhtml source file artifact is generated.
Replace the hard-coded references to "index" files and allow the base filename (e.g. index) to be configurable. The configuration key is to be mummy.collectionContentBaseNames and accept a collection (normally a list) of strings.