datastore.save({
  key: datastore.key('Kind'),
  data: {
    longString: longString,
    notMetadata: true,
    metadata: {
      longString: longString,
      otherProperty: 'value',
      longStringArray: [
        {
          longString: longString,
          nestedLongStringArray: [
            {
              longString: longString,
              nestedProperty: true
            },
            {
              longString: longString
            }
          ]
        }
      ]
    }
  },
  excludeFromIndexes: [
    'longString',
    'metadata.longString',
    'metadata.longStringArray[].longString',
    'metadata.longStringArray[].nestedLongStringArray[].longString'
  ]
})