Filter generator allows you to hide from your structure issues that don't pass certain criteria. You can use JQL, Text and S-JQL queries.
Once you add this generator, you will only see the items from the structure that pass the query and their parents. The parents are necessary to show the issues without breaking the hierarchy.
- All filters have an option to show not only matching issues, but also all their descendant. Select the Show all sub-items of matching items option in the generator settings to enable this.
- JQL Filter has an option that allows you to keep non-issues as you apply the filter. Since the folders and other types of items are not returned by the JQL, this is the only way to tell the filter not to remove them.
Filtering by Sprint (and predefined Hide Closed Sprints) is limited to inserted structure(s), not to the whole structure. Also, as these filters apply to Sprint folders rather than issues themselves, Show all sub-items of matching items is made redundant.