azure-sdk-for-net: [BUG] Service Bus: Unknown error after calling GetNamespaceInfo

Describe the bug When I call client.GetNamespaceInfoAsync it is returning an exception. The message shows an “unknown error”.

Expected behavior Throw an error that is not unknown or successful.

Actual behavior (include Exception or Stack Trace) Returning unknown error.

To Reproduce Steps to reproduce the behavior (include a code snippet, screenshot, or any additional information that might help us reproduce the issue)

1. start the clientManagement
2. call GetNamespaceInfoAsync

   at Microsoft.Azure.ServiceBus.Management.NamespaceInfoExtensions.ParseFromContent(String xml)
   at Microsoft.Azure.ServiceBus.Management.ManagementClient.<GetNamespaceInfoAsync>d__9.MoveNext()
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()

Environment:

• Name and version of the Library package used: Microsoft.Azure.ServiceBus 5.1.3
• Hosting platform or OS and .NET runtime version (dotnet --info output for .NET Core projects): [e.g. Azure AppService or Windows 10 .NET Framework 4.8] netstandard2.1, called by netcoreapp3.1
• IDE and version : [e.g. Visual Studio 16.3] VS16.10