fix(#1): this commit adds filtering by multiple identifiers

Author: https-richardy

Source/HttpsRichardy.Federation.Domain/Filtering/Builders/GroupFiltersBuilder.cs

@@ -3,6 +3,18 @@ namespace HttpsRichardy.Federation.Domain.Filtering.Builders;
 public sealed class GroupFiltersBuilder :
     FiltersBuilderBase<GroupFilters, GroupFiltersBuilder>
 {
+    public GroupFiltersBuilder WithIdentifiers(string[] identifiers)
+    {
+        var validIdentifiers = identifiers?
+            .Where(identifier => !string.IsNullOrWhiteSpace(identifier))
+            .ToArray();
+
+        if (validIdentifiers?.Length > 0)
+            _filters.Identifiers = validIdentifiers;
+
+        return this;
+    }
+
     public GroupFiltersBuilder WithRealmId(string? realmId)
     {
         _filters.RealmId = realmId;

Source/HttpsRichardy.Federation.Domain/Filtering/GroupFilters.cs

@@ -4,6 +4,7 @@ public sealed class GroupFilters : Filters
 {
     public string? RealmId { get; set; }
     public string? Name { get; set; }
+    public string[]? Identifiers { get; set; }
 
     public static GroupFiltersBuilder WithSpecifications() => new();
 }