Streamline some GroupBy overloads.

Ix.NET/Source/System.Linq.Async/System/Linq/Operators/GroupBy.cs

@@ -64,7 +64,7 @@ namespace System.Linq
             if (elementSelector == null)
                 throw Error.ArgumentNull(nameof(elementSelector));
 
-            return source.GroupBy(keySelector, elementSelector, EqualityComparer<TKey>.Default);
+            return new GroupedAsyncEnumerable<TSource, TKey, TElement>(source, keySelector, elementSelector, EqualityComparer<TKey>.Default);
         }
 
         public static IAsyncEnumerable<IAsyncGrouping<TKey, TElement>> GroupBy<TSource, TKey, TElement>(this IAsyncEnumerable<TSource> source, Func<TSource, TKey> keySelector, Func<TSource, TElement> elementSelector, IEqualityComparer<TKey> comparer)
@@ -90,7 +90,7 @@ namespace System.Linq
             if (elementSelector == null)
                 throw Error.ArgumentNull(nameof(elementSelector));
 
-            return source.GroupBy(keySelector, elementSelector, EqualityComparer<TKey>.Default);
+            return new GroupedAsyncEnumerableWithTask<TSource, TKey, TElement>(source, keySelector, elementSelector, EqualityComparer<TKey>.Default);
         }
 
         public static IAsyncEnumerable<IAsyncGrouping<TKey, TElement>> GroupBy<TSource, TKey, TElement>(this IAsyncEnumerable<TSource> source, Func<TSource, Task<TKey>> keySelector, Func<TSource, Task<TElement>> elementSelector, IEqualityComparer<TKey> comparer)
@@ -116,7 +116,7 @@ namespace System.Linq
             if (resultSelector == null)
                 throw Error.ArgumentNull(nameof(resultSelector));
 
-            return GroupBy(source, keySelector, resultSelector, EqualityComparer<TKey>.Default);
+            return new GroupedResultAsyncEnumerable<TSource, TKey, TResult>(source, keySelector, resultSelector, EqualityComparer<TKey>.Default);
         }
 
         public static IAsyncEnumerable<TResult> GroupBy<TSource, TKey, TResult>(this IAsyncEnumerable<TSource> source, Func<TSource, TKey> keySelector, Func<TKey, IAsyncEnumerable<TSource>, TResult> resultSelector, IEqualityComparer<TKey> comparer)
@@ -142,7 +142,7 @@ namespace System.Linq
             if (resultSelector == null)
                 throw Error.ArgumentNull(nameof(resultSelector));
 
-            return GroupBy(source, keySelector, resultSelector, EqualityComparer<TKey>.Default);
+            return new GroupedResultAsyncEnumerableWithTask<TSource, TKey, TResult>(source, keySelector, resultSelector, EqualityComparer<TKey>.Default);
         }
 
         public static IAsyncEnumerable<TResult> GroupBy<TSource, TKey, TResult>(this IAsyncEnumerable<TSource> source, Func<TSource, Task<TKey>> keySelector, Func<TKey, IAsyncEnumerable<TSource>, Task<TResult>> resultSelector, IEqualityComparer<TKey> comparer)