Enable nullability in Content.Server (#3685)

Content.IntegrationTests/DummyGameTicker.cs

@@ -1,10 +1,12 @@
+#nullable enable
 using System;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using Content.Server.GameTicking;
 using Content.Server.Interfaces.GameTicking;
-using Content.Shared.Roles;
-using Content.Shared.Preferences;
 using Content.Server.Mobs;
+using Content.Shared.Preferences;
+using Content.Shared.Roles;
 using Robust.Server.Player;
 using Robust.Shared.GameObjects;
 using Robust.Shared.Map;
@@ -60,7 +62,7 @@ namespace Content.IntegrationTests
         {
         }
 
-        public void MakeJoinGame(IPlayerSession player, string jobId)
+        public void MakeJoinGame(IPlayerSession player, string? jobId)
         {
         }
 
@@ -76,7 +78,7 @@ namespace Content.IntegrationTests
         public EntityCoordinates GetJobSpawnPoint(string jobId) => EntityCoordinates.Invalid;
         public EntityCoordinates GetObserverSpawnPoint() => EntityCoordinates.Invalid;
 
-        public void EquipStartingGear(IEntity entity, StartingGearPrototype startingGear, HumanoidCharacterProfile profile)
+        public void EquipStartingGear(IEntity entity, StartingGearPrototype startingGear, HumanoidCharacterProfile? profile)
         {
         }
 
@@ -85,7 +87,12 @@ namespace Content.IntegrationTests
             return new();
         }
 
-        public bool HasGameRule(Type type)
+        public bool HasGameRule(string? type)
+        {
+            return false;
+        }
+
+        public bool HasGameRule(Type? type)
         {
             return false;
         }
@@ -96,7 +103,7 @@ namespace Content.IntegrationTests
 
         public IEnumerable<GameRule> ActiveGameRules { get; } = Array.Empty<GameRule>();
 
-        public bool TryGetPreset(string name, out Type type)
+        public bool TryGetPreset(string name, [NotNullWhen(true)] out Type? type)
         {
             type = default;
             return false;