How to have an auto increment primary key in HDBDD

Hello,

Using a HDBDD file I am creating a table in which I need a primary key(recordId) which is auto generated by the DB.
What would be the way to do this?

My hdbdd file:

namespace sap.mobile.data;

        @Schema : 'SAP_TEST'

context Sample {

@Catalog.tableType : #COLUMN

  entity Details {

  text : LargeString;

  level : String(10);

  timestamp : UTCTimestamp;

  recordId : ?

  };

}