js/libs/ember-data.js
function(record, json, relationship) {
    var key   = relationship.key,
        attrs = get(this, 'attrs'),
        embed = attrs && attrs[key] && attrs[key].embedded === 'always';

    if (embed) {
      json[this.keyForAttribute(key)] = get(record, key).map(function(relation) {
        var data = relation.serialize(),
            primaryKey = get(this, 'primaryKey');

        data[primaryKey] = get(relation, primaryKey);

        return data;
      }, this);
    }
  }
function(record, json, relationship) {
    var key   = relationship.key,
        attrs = get(this, 'attrs'),
        embed = attrs && attrs[key] && attrs[key].embedded === 'always';

    if (embed) {
      json[this.keyForAttribute(key)] = get(record, key).map(function(relation) {
        var data = relation.serialize(),
            primaryKey = get(this, 'primaryKey');

        data[primaryKey] = get(relation, primaryKey);

        return data;
      }, this);
    }
  }
Serialize has-may relationship when it is configured as embedded objects.

@method serializeHasMany