Initial mirror.

MareSynchronosAPI/Data/Comparer/GroupDataComparer.cs

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+namespace MareSynchronos.API.Data.Comparer;
+
+public class GroupDataComparer : IEqualityComparer<GroupData>
+{
+    public static GroupDataComparer Instance => _instance;
+    private static GroupDataComparer _instance = new GroupDataComparer();
+
+    private GroupDataComparer() { }
+    public bool Equals(GroupData? x, GroupData? y)
+    {
+        if (x == null || y == null) return false;
+        return x.GID.Equals(y.GID, StringComparison.Ordinal);
+    }
+
+    public int GetHashCode(GroupData obj)
+    {
+        return obj.GID.GetHashCode();
+    }
+}