If the handle for the "dso" already exists in the index, and the "dso"
has a lastModified timestamp that is newer than the document in the index
then it is updated, otherwise a new document is added.
If the handle for the "dso" already exists in the index, and the "dso"
has a lastModified timestamp that is newer than the document in the index
then it is updated, otherwise a new document is added.