9.0 - GetAliasResponse is initialized with Aliases set to null instead of empty

[Ramstad]

Elastic.Clients.Elasticsearch version: 9.0.0

Elasticsearch version: 9.0.0

.NET runtime version: net9.0

Operating system version: Windows for client, docker for elasticsearch

Description of the problem including expected versus actual behavior:
GetAliasResponse is now initialized with Aliases being null instead of empty dictionary. This causes IsValidResponse and the depending DebugInformation to fail with System.NullReferenceException when no matching alias exists.
Expected result is for IsValidResponse not to throw, either by dictionary being empty, or by checking for nulls.