Add test coverage of getting last object time

osu.Game.Tests/Beatmaps/Formats/LegacyBeatmapDecoderTest.cs

@@ -314,6 +314,24 @@ public void TestDecodeBeatmapColours()
             }
         }
 
+        [Test]
+        public void TestGetLastObjectTime()
+        {
+            var decoder = new LegacyBeatmapDecoder();
+
+            using (var resStream = TestResources.OpenResource("mania-last-object-not-latest.osu"))
+            using (var stream = new LineBufferedReader(resStream))
+            {
+                var beatmap = decoder.Decode(stream);
+
+                Assert.That(beatmap.HitObjects.Last().StartTime, Is.EqualTo(2494));
+                Assert.That(beatmap.HitObjects.Last().GetEndTime(), Is.EqualTo(2494));
+
+                Assert.That(beatmap.HitObjects.Max(h => h.GetEndTime()), Is.EqualTo(2582));
+                Assert.That(beatmap.GetLastObjectTime(), Is.EqualTo(2582));
+            }
+        }
+
         [Test]
         public void TestDecodeBeatmapComboOffsetsOsu()
         {

osu.Game.Tests/Resources/mania-last-object-not-latest.osu

@@ -0,0 +1,39 @@
+osu file format v14
+
+[General]
+SampleSet: Normal
+StackLeniency: 0.7
+Mode: 3
+
+[Difficulty]
+HPDrainRate:3
+CircleSize:5
+OverallDifficulty:8
+ApproachRate:8
+SliderMultiplier:3.59999990463257
+SliderTickRate:2
+
+[TimingPoints]
+24,352.941176470588,4,1,1,100,1,0
+6376,-50,4,1,1,100,0,0
+
+[HitObjects]
+51,192,24,1,0,0:0:0:0:
+153,192,200,1,0,0:0:0:0:
+358,192,376,1,0,0:0:0:0:
+460,192,553,1,0,0:0:0:0:
+460,192,729,128,0,1435:0:0:0:0:
+358,192,906,128,0,1612:0:0:0:0:
+256,192,1082,128,0,1788:0:0:0:0:
+153,192,1259,128,0,1965:0:0:0:0:
+51,192,1435,128,0,2141:0:0:0:0:
+51,192,2318,1,12,0:0:0:0:
+153,192,2318,1,4,0:0:0:0:
+256,192,2318,1,6,0:0:0:0:
+358,192,2318,1,14,0:0:0:0:
+460,192,2318,1,0,0:0:0:0:
+51,192,2494,128,0,2582:0:0:0:0:
+153,192,2494,128,14,2582:0:0:0:0:
+256,192,2494,128,6,2582:0:0:0:0:
+358,192,2494,128,4,2582:0:0:0:0:
+460,192,2494,1,12,0:0:0:0:0: