Right now, the BatchXMLFileFilter accept function does not properly handle the following case:
this will return no files even if there are .txt files in the directory. Right now, we have worked around this by requiring glob syntax when a regex is specified: https://github.com/caskdata/hydrator-plugins/pull/651 but that isn't the root problem.
1. create unit tests for this class if they do not exist
2. verify that the class returns no files when given the input
3. fix the issue by referencing BatchFileFilter.java
4. verify it now passes unit tests
5. remove the verification step from https://github.com/caskdata/hydrator-plugins/pull/651