fix build. (#4192)

Author: GarrettBeatty

sdk/src/Services/S3/Custom/Transfer/Internal/BufferedPartDataHandler.cs

@@ -99,7 +99,7 @@ public async Task ProcessPartAsync(
         {
             if (partNumber == _partBufferManager.NextExpectedPartNumber)
             {
-                await ProcessStreamingPartAsync(partNumber, response, cancellationToken).ConfigureAwait(false);
+                ProcessStreamingPart(partNumber, response);
             }
             else
             {
@@ -113,7 +113,6 @@ public async Task ProcessPartAsync(
         /// </summary>
         /// <param name="partNumber">The part number being processed.</param>
         /// <param name="response">The GetObjectResponse containing the part data. Ownership is transferred to StreamingDataSource.</param>
-        /// <param name="cancellationToken">Cancellation token for the operation.</param>
         /// <remarks>
         /// This method is called when the part arrives in the expected sequential order, allowing
         /// for optimal zero-copy streaming directly to the consumer without buffering into memory.
@@ -129,10 +128,9 @@ public async Task ProcessPartAsync(
         /// - If constructor succeeds but AddBufferAsync fails: StreamingDataSource.Dispose() handles the response
         /// - If AddBufferAsync succeeds: Buffer manager owns everything and will clean up
         /// </remarks>
-        private async Task ProcessStreamingPartAsync(
+        private void ProcessStreamingPart(
             int partNumber,
-            GetObjectResponse response, 
-            CancellationToken cancellationToken)
+            GetObjectResponse response)
         {
             _logger.DebugFormat("BufferedPartDataHandler: [Part {0}] Matches NextExpectedPartNumber - streaming directly without buffering",
                 partNumber);

sdk/test/Services/S3/UnitTests/Custom/PartBufferManagerTests.cs

@@ -1006,7 +1006,7 @@ public async Task AddBufferAsync_IPartDataSource_WithBufferedDataSource_AddsSucc
 
         [TestMethod]
         [ExpectedException(typeof(ArgumentNullException))]
-        public async Task AddBufferAsync_IPartDataSource_WithNull_ThrowsArgumentNullException()
+        public void AddBufferAsync_IPartDataSource_WithNull_ThrowsArgumentNullException()
         {
             // Arrange
             var config = MultipartDownloadTestHelpers.CreateBufferedDownloadConfiguration();