The default implicit constructor must also have a doc comment, so I have to make it explicit and either properly restrict the visibility of the constructor, or actually document it.
The default player has a fixed name and uuid that should never collide with existing players.
It will never have self permission data, and it will always be part of the default groups.
It is useful for anonymous permission test (for instance, listing only the servers that are publicly visible for the ping server list)
