This reverts commit 3c3e860dbc. Closes https://github.com/ppy/osu/issues/11491.
3c3e860dbc
# Conflicts: # osu.Game/Beatmaps/Beatmap.cs
using
Also ensures some extra fields inside Beatmap have non-null defaults.
Also fixes circular references when using IJsonSerializable.
# Conflicts: # osu.Game.Rulesets.Mania/UI/Column.cs