V4: Fixed an issue where NullReferenceException was thrown while invoking AmazonCloudFormationClient.UpdateStackAsync().

[ashishdhingra]

Description

Fixed an issue where NullReferenceException was thrown while invoking AmazonCloudFormationClient.UpdateStackAsync().

Motivation and Context

Issue #3824

Testing

• Added integration test.
• Dry-run DRY_RUN-85255203-68f8-4723-b60b-bac707e8620b completed successfully.

Screenshots (if appropriate)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• My code follows the code style of this project
• My change requires a change to the documentation
• I have updated the documentation accordingly
• I have read the README document
• I have added tests to cover my changes
• All new and existing tests passed

License

• I confirm that this pull request can be released under the Apache 2 license

[normj]

Since null means we don't want to send string.Empty for NotificationARNs this logic can be simplified. Here is my suggestion without testing it.

if (updateStackRequest != null)
{
	var arns = updateStackRequest.NotificationARNs;
	if (arns != null)
	{
		// if there are no NotificationARNs and the list was created by user (type is NOT AutoConstructed)
		// only then pass empty param
		if (arns.Count == 0 && !(arns is AutoConstructedList<string>))
		{
			request.Parameters.Add("NotificationARNs", "");
			if (request.Parameters.ContainsKey("NotificationARNs"))
			{
				request.Parameters["NotificationARNs"] = string.Empty;
			}
			else
			{
				request.Parameters.Add("NotificationARNs", string.Empty);
			}
		}				
	}
}

[ashishdhingra]

Fixed. Re-executing dry-run.