on Email Message Created Subscription
open suspend fun onEmailMessageCreatedSubscription(owner: String, onSubscriptionEstablished: Consumer<GraphQLResponse<OnEmailMessageCreatedSubscription.Data>>, onSubscription: Consumer<GraphQLResponse<OnEmailMessageCreatedSubscription.Data>>, onSubscriptionCompleted: Action, onFailure: Consumer<ApiException>): GraphQLOperation<OnEmailMessageCreatedSubscription.Data>?