Subscription trigger not working

[Loschcode]

I've got a subscription such as

module Subscriptions
  class SubscribeToBullshit < Mutations::BaseMutation
    description 'yes'

    field :id, String, null: true
    field :first_name, String, null: true
    field :last_name, String, null: true

    def resolve
      return unless current_identity

      {
        id: current_identity.id,
        first_name: current_identity.first_name,
        last_name: current_identity.last_name
      }
    end
  end
end

Which's plugged on my schema this way

module Types
  class SubscriptionType < GraphQL::Schema::Object
    field :subscribeToBullshit, resolver: Subscriptions::SubscribeToBullshit
  end
end

And finally the schema declaration as so

class MySchema < GraphQL::Schema
  mutation Types::MutationType
  query Types::QueryType
  subscription Types::SubscriptionType
end

On my front-end I subscribe to subscribeToBullshit successfully through a command which is like that

subscription SubscribeToBullshit {
  subscribeToBullshit {
    id
    firstName
    lastName
  }
}

The subscription from my front-end is successful. I now want to trigger the update from my server, inside a mutation, to be sent to the different clients listening to subscribeToBullshit

module Mutations
  class StoreIdentityName < Mutations::BaseMutation
    def resolve
     # some logic around
     MySchema.subscriptions.trigger('subscribeToBullshit', {}, {
        id: current_identity.id,
        first_name: current_identity.first_name,
        last_name: current_identity.last_name
      })
    end
  end
end

I don't think the detail of the mutation matters. when I check MySchema.subscriptions it returns nil and will systematically cause an error. Is the documentation up-to-date on this matter?

undefined method `trigger' for nil:NilClass

What am I doing wrong here?

[Loschcode]

I figured you have to add use GraphQL::Subscriptions::ActionCableSubscriptions at the beginning of your schema, #2091 gave the way.

You should add this detail in https://graphql-ruby.org/subscriptions/triggers.html as it's quite important to know, I could never guess ...