Missing packages in github.com/grpc-ecosystem/go-grpc-middleware upgrading from v1 to v2

Question

Migrating from v1 to v2 in github.com/grpc-ecosystem/go-grpc-middleware and didn't see muB := grpc_testing.NewMutexReadWriter(b)

Link for old package: - https://pkg.go.dev/github.com/grpc-ecosystem/[email protected]/testing#MutexReadWriter

Migrating github.com/grpc-ecosystem/go-grpc-middleware from v1 to v2, need suggestion where i can find NewMutexReadWriter struct?