How to use the ember-graphql-adapter/types.SelectionSet function in ember-graphql-adapter

currentModel.eachRelationship((relName, relationship) => {
          let field;
          let { type, options } = relationship;

          if (options.async) {
            field = this._buildAsyncRelationship(relName, relationship);
          } else {
            let relModel = store.modelFor(type);
            if (this.visited.indexOf(relName) === -1) {
              field = new Type.Field(
                this.normalizeCaseFn(relName),
                null,
                new Type.ArgumentSet(),
                new Type.SelectionSet()
              );
              this.agenda.push({ name: relName, model: relModel, field });
            }
          }
          if (field) {
            currentField.selectionSet.push(field);
          }
        });
      }