message: add to getMassProperties
diff: @@ -1154,7 +1154,9 @@ export class IModelDb extends IModel {
  }
  }
  - /** Get the mass properties for the supplied elements */
  + /** Get the mass properties for the supplied elements
  + * @beta
  + */
  public async getMassProperties(requestContext: ClientRequestContext, props: MassPropertiesRequestProps): Promise<MassPropertiesResponseProps> {
  requestContext.enter();
  const resultString: string = this.nativeDb.getMassProperties(JSON.stringify(props));
  