fix(.NET): Improve Collection of Errors string

[texastony]

Issue #, if available:

Collection of Errors is a frustrating error because it requires customer action
to completely serialize it into logs.

We can make a simple fix in .NET to improve the CX,
by always serializing the list into the Collection Of Error's
message.

We concatenate the given error message with
a serialization of all the nested errors.

See similar PR for MPL-Java: 9e195a1

Squash/merge commit message, if applicable:

fix(.NET): Improve Collection of Errors string 

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[rishav-karanjit]

Looks good to me

Got 2 new comments

[rishav-karanjit]

Are we skipping https://github.com/aws/aws-cryptographic-material-providers-library/blob/main/TestVectorsAwsCryptographicMaterialProviders/runtimes/net/Generated/KeyVectors/CollectionOfErrors.cs because its a test?

Dismissing for this question

#1158 (review)

[rishav-karanjit]

We are not importing System.Collections.Generic.List

Suggested change

	private static string ListAsString(List<Exception> list)
	private static string ListAsString(System.Collections.Generic.List<Exception> list)

Here and other places

[texastony]

See aws/aws-encryption-sdk#728 (comment)

[rishav-karanjit]

We are missing a import here. Thats why its a blocking comment.

For example: when I try to run this (below) it works but if I remove using System.Collections.Generic it will give me an error.

using System;
using System.Collections.Generic;

public class HelloWorld
{
    public static void Main(string[] args)
    {
        // Create a new List of strings
        List<string> names = new List<string>();

        // Add items to the list
        names.Add("Alice");
        names.Add("Bob");
        names.Add("Charlie");

        // Print all items in the list
        Console.WriteLine("All names:");
        foreach (string name in names)
        {
            Console.WriteLine(name);
        }
    }
}

[rishav-karanjit]

Also, I guess the CI is passing because it only checks for output.Failure? but not output.error.TypeOfError?

[texastony]

Yes, you nailed it.
I got it to work for one of the three PRs, and did not verify across all three repos.

Great catch.

[texastony]

Are we skipping https://github.com/aws/aws-cryptographic-material-providers-library/blob/main/TestVectorsAwsCryptographicMaterialProviders/runtimes/net/Generated/KeyVectors/CollectionOfErrors.cs because its a test?

Yes. There is no customer impact, so I am not inclined to increase our Beneration scope.