Many-to-One unique denormalization does not work as expected

[Floriferous]

When you link 2 collections together in a many-to-one/unique way, it is not possible to get denormalization to work properly. This is because of Meteor-Community-Packages/denormalize#17, so for now, nothing can be done to fix this.

const A = new Meteor.Collection('a');
const B = new Meteor.Collection('b');

A.addLinks({
  b: {
    field: 'bLinks',
    type: 'many',
    collection: B,
    unique: true,
  },
});

B.addLinks({
  a: {
    inversedBy: 'b',
    collection: A,
    denormalize: {
      field: 'aCache',
      body: { _id: 1 },
    },
  },
});

const bId = B.insert({});
A.insert({ bLinks: [{ _id: bId }] });

B.findOne({ _id: bId })
// Returns { aCache: [{ _id: 'xxx' }] }
// Expected { aCache: { _id: 'xxx' } }