get Contacts By User Id
fun getContactsByUserId(userId: String, onCompletion: (Either<List<Contact>, SippoResourceError>) -> Unit)
Fetches contacts from the specified userId.
Parameters
user Id
user Id to be fetched.
on Completion
Callback that will be invoked when the request is completed. It will receive the contact list in case of success or a SippoResourceError otherwise.