Catalog java artifacts by file name without requiring content

Today we collect initial java metadata from the file name and grab additional information to claim the existence of a package (such as a pom.properties or manifest). We should consider allowing only the presence of a jar (or similar) and the filename metadata plus the presence of one or more `*.class` files being present to be the minimum required information needed to create a package.

No files or tests are named. Start by locating the Java artifact cataloging logic and the checks that require pom.properties or a manifest; then determine how jar filenames and *.class presence are represented. Done means a jar or similar artifact can create a package from filename metadata plus one or more *.class files without content metadata.

Written by the indexing model from the issue text.