Vulcan/packages/vulcan-payments/lib/server/mutations.js

import { GraphQLSchema, Collections } from 'meteor/vulcan:core';
// import Users from 'meteor/vulcan:users';
import { createCharge } from '../server/integrations/stripe.js';

const resolver = {
  Mutation: {
    async createChargeMutation(root, args, context) {
      return await createCharge(args);
    },
  },
};
GraphQLSchema.addResolvers(resolver);
GraphQLSchema.addMutation('createChargeMutation(token: JSON, userId: String, productKey: String, associatedCollection: String, associatedId: String, properties: JSON) : Chargeable');

const chargeableSchema = `
  union Chargeable = ${Collections.map(collection => collection.typeName).join(' | ')}
`;
GraphQLSchema.addSchema(chargeableSchema);

const resolverMap = {
  Chargeable: {
    __resolveType(obj, context, info){
      return obj.__typename || null;
    },
  },
};
GraphQLSchema.addResolvers(resolverMap);