With the addition of the Microsoft.Extensions libraries, we've added another "hashing helper" type to our repo: https://github.com/dotnet/runtime/blob/327801e8b838b97950cb8daaeef724acbe4e3c5f/src/libraries/Common/src/Extensions/HashCodeCombiner/HashCodeCombiner.cs#L11 We should move all usages of this to one of the existing "hashing helper" options we already have.