This update introduces 1.17 support. As 1.17 is the native version, ProtocolLib will be required if the display-name.visibility 'NEARBY' is used. 1.15 support has been dropped, as at this point there's little reason to not use 1.16.5.
The plugin is also now compiled using Java 16, so you will need to be using Java 16 to use this plugin.