refactor(llc): make Filter.empty constructor const.

Signed-off-by: xsahil03x <[email protected]>

packages/stream_chat/lib/src/core/models/filter.dart

@@ -102,6 +102,12 @@ class Filter extends Equatable {
     this.key,
   }) : operator = operator.rawValue;
 
+  /// An empty filter
+  const Filter.empty()
+      : value = const {},
+        operator = null,
+        key = null;
+
   /// Combines the provided filters and matches the values
   /// matched by all filters.
   factory Filter.and(List<Filter> filters) =>
@@ -172,9 +178,6 @@ class Filter extends Equatable {
     String? key,
   }) = Filter.__;
 
-  /// An empty filter
-  factory Filter.empty() => const Filter.raw(value: {});
-
   /// Creates a custom [Filter] from a raw map value
   ///
   /// ```dart

packages/stream_chat/test/src/core/models/filter_test.dart

@@ -139,7 +139,7 @@ void main() {
     });
 
     test('empty', () {
-      final filter = Filter.empty();
+      const filter = Filter.empty();
       expect(filter.value, {});
     });