A-Lion | A sketch plugin to align your layers to a key layer | Image Editing library

@rseddon's comment was the missing step. In the sprit of documentation, here are the exact settings I used when it was working:

• Create a new role "limited-anon" with "nx-repository-view-maven2--*-read" and "nx-search-read"
• Under users, go to "Anonymous". Remove the built in role and add "limited-anon"
• Create a content selector with search expression "coordinate.groupId =^ "my.package.name"
• Create a privilege of type "Repository Content Selector" going against this content selector, the snapshot repository and actions "read,edit,browse"
• Create a similar privilege for the releases repo
• Create a new role with both of these privileges
• Assign both that new role and "limited-anon" to Sam (the user who can see the artifacts)
• Assign just "limited-anon" to the other test user

This configuration works for:

• anonymous user - can not see this artifact
• Sam - can see this artifact
• other user - cannot see this artifact

With this setup, it looks like items in the repository without content selectors cannot be seen unless you are an admin. Which is fine for my use case.