maven jar-loader: Initalise files, add archive format.

swh/core/tarball.py

@@ -177,6 +177,7 @@ def compress(tarpath, nature, dirpath_or_files):
 ADDITIONAL_ARCHIVE_FORMATS = [
     # name  , extensions, function
     ("tar.Z|x", [".tar.Z", ".tar.x"], _unpack_tar),
+    ("jar", [".jar"], _unpack_zip),
     # FIXME: make this optional depending on the runtime lzip package install
     ("tar.lz", [".tar.lz"], _unpack_tar),
 ]