code: function forwardsManyToOneDescriptor(fieldName, declaredToModelName) {
      return {
          get() {
              const {
                  session: {
                      [declaredToModelName]: DeclaredToModel,
                  },
              } = this.getClass();
              const {
                  [fieldName]: toId,
              } = this._fields;
  
              return DeclaredToModel.withId(toId);
          },
          set(value) {
              this.update({
                  [fieldName]: normalizeEntity(value),
              });
          },
      };
  }
docs: Forwards direction of a Foreign Key: returns one object.
  Also works as {@link .forwardsOneToOneDescriptor|forwardsOneToOneDescriptor}.
  
  For `book.author` referencing an `Author` model instance,
  `fieldName` would be `'author'` and `declaredToModelName` would be `'Author'`.
  @param  {string} fieldName - the name of the field the descriptor will be assigned to.
  @param  {string} declaredToModelName - the name of the model that the field references.