[BUG] Call BlobAccessPolicy.StartsOn on a policy without Start Time, will make progress crash and exist

[blueww]

Describe the bug
Please provide the description of issue you're seeing.
On "Azure.Storage.Blobs" Version="12.5.1", when try to call BlobAccessPolicy.StartsOn on a policy without Start/Expire Time, The whole process will crash and exist, even try catch can't catch the exception.

This a regression from 12.5.0-preview.6

Expected behavior
What is the expected behavior?
It seems BlobAccessPolicy.StartsOn is replaced with "PolicyStartsOn". If so, we should make build fail when use "StartsOn", or make the "StartOn" still work although not suggest to use.

Actual behavior (include Exception or Stack Trace)
What is the actual behavior?

Currently：

1. The old code write with "StartsOn" will make program crash , and try catch not work. ( Like when powershell call the code, the whole PSH console will disappear.) Error is:

System.StackOverflowException
HResult=0x800703E9
Message=Exception of type 'System.StackOverflowException' was thrown.

2. When user debug the program and try to expand the AccessPolicy object in Watch window, will get error:

---------------------------
Microsoft Visual Studio
---------------------------
The target process exited with code -2147023895 while evaluating the function 'Azure.Storage.Blobs.Models.BlobAccessPolicy.ExpiresOn.get'.

If the problem happens regularly, consider disabling the Tools->Options setting "Debugging->General->Enable property evaluation and other implicit function calls" or debugging the cause by evaluating the expression from the Immediate window. See help for information on doing this.
---------------------------
OK   Help   
---------------------------

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

Following code can repro the issue:

            BlobAccessPolicy AccessPolicy = new BlobAccessPolicy()
            {
                Permissions = "rw"
            };
            Console.WriteLine(AccessPolicy.ExpiresOn); // crash happen here
            Console.WriteLine(AccessPolicy.StartsOn);

Environment:

• Name and version of the Library package used: [e.g. Azure.Storage.Blobs 12.5.1]
• 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]

.NET Core SDK (reflecting any global.json):
 Version:   2.2.108
 Commit:    33ed5b90ce

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.18363
 OS Platform: Windows
 RID:         win10-x64
 Base Path:   C:\Program Files\dotnet\sdk\2.2.108\

Host (useful for support):
  Version: 2.2.6
  Commit:  7dac9b1b51

.NET Core SDKs installed:
  2.2.108 [C:\Program Files\dotnet\sdk]

.NET Core runtimes installed:
  Microsoft.AspNetCore.All 2.2.6 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.App 2.2.6 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 2.2.6 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]

To install additional .NET Core runtimes or SDKs:
  https://aka.ms/dotnet-download

• IDE and version : [e.g. Visual Studio 16.3]
  VS 15.7.4

[ghost]

Thanks for the feedback! We are routing this to the appropriate team for follow-up. cc @xgithubtriage.

[jsquire]

Thank you for your feedback. Tagging and routing to the team best able to assist.

[seanmcc-msft]

Hi @blueww, I'll put out a fix for this, but StartsOn and ExpiresOn are deprecated. I recommend using PolicyStartsOn and PolicyExpirieOn instead.

[blueww]

@seanmcc-msft
Thanks for the fix!
We have already switch to PolicyStartsOn and PolicyExpirieOn in PSH code.
We need the fix as when we debug the code and expand AccessPolicy object in Watch window, the whole process will crash.