feat: always reset stream position after call to serializer (#235)

* feat: always reset stream position after call to serializer

* docs: remove setting stream position from custom serializer sample

Author: daveleek

README.md

@@ -533,7 +533,6 @@ public class NewtonsoftJson7Serializer : IJsonSerializer
             Serializer.Serialize(jsonWriter, instance);
 
             jsonWriter.Flush();
-			stream.Position = 0;
         }
     }
 

src/Unleash/Communication/UnleashApiClient.cs

@@ -187,6 +187,7 @@ public async Task<bool> RegisterClient(ClientRegistration registration, Cancella
 
             var memoryStream = new MemoryStream();
             jsonSerializer.Serialize(memoryStream, registration);
+            memoryStream.Position = 0;
 
             const int bufferSize = 1024 * 4;
 
@@ -233,6 +234,7 @@ public async Task<bool> SendMetrics(ThreadSafeMetricsBucket metrics, Cancellatio
                     InstanceId = clientRequestHeaders.InstanceTag,
                     Bucket = bucket
                 });
+                memoryStream.Position = 0;
             }
 
             const int bufferSize = 1024 * 4;