Fix detecting message accept encoding with whitespace (grpc#1882)

Author: JamesNK

src/Grpc.AspNetCore.Server/Internal/HttpContextServerCallContext.cs

@@ -531,6 +531,8 @@ internal bool IsEncodingInRequestAcceptEncoding(string encoding)
                         segment = acceptEncoding;
                     }
 
+                    segment = segment.Trim();
+
                     // Check segment
                     if (segment.SequenceEqual(encoding))
                     {

test/FunctionalTests/Server/CompressionTests.cs

@@ -430,11 +430,13 @@ public async Task SendCompressedMessageWithoutEncodingHeader_ServerErrorResponse
             AssertHasLogRpcConnectionError(StatusCode.Internal, "Request did not include grpc-encoding value with compressed message.");
         }
 
-        [TestCase("gzip", true)]
+        [TestCase("gzip", "gzip", true)]
+        [TestCase("gzip", "identity, gzip", true)]
+        [TestCase("gzip", "gzip ", true)]
 #if NET6_0_OR_GREATER
-        [TestCase("deflate", false)]
+        [TestCase("deflate", "deflate", false)]
 #endif
-        public async Task SendCompressedMessageAndReturnResultWithNoCompressFlag_ResponseNotCompressed(string algorithmName, bool algorithmSupportedByServer)
+        public async Task SendCompressedMessageAndReturnResultWithNoCompressFlag_ResponseNotCompressed(string algorithmName, string messageAcceptEncoding, bool algorithmSupportedByServer)
         {
             // Arrange
             var requestMessage = new HelloRequest
@@ -447,7 +449,7 @@ public async Task SendCompressedMessageAndReturnResultWithNoCompressFlag_Respons
 
             var httpRequest = GrpcHttpHelper.Create("Compression.CompressionService/WriteMessageWithoutCompression");
             httpRequest.Headers.Add(GrpcProtocolConstants.MessageEncodingHeader, algorithmName);
-            httpRequest.Headers.Add(GrpcProtocolConstants.MessageAcceptEncodingHeader, algorithmName);
+            httpRequest.Headers.Add(GrpcProtocolConstants.MessageAcceptEncodingHeader, messageAcceptEncoding);
             httpRequest.Content = new GrpcStreamContent(requestStream);
 
             // Act