espocrm-base/application/Espo/Resources/metadata/app/relationships.json

{
    "attachments": {
        "converterClassName": "Espo\\Core\\Utils\\Database\\Orm\\LinkConverters\\Attachments"
    },
    "emailEmailAddress": {
        "converterClassName": "Espo\\Core\\Utils\\Database\\Orm\\LinkConverters\\EmailEmailAddress"
    },
    "entityTeam": {
        "converterClassName": "Espo\\Core\\Utils\\Database\\Orm\\LinkConverters\\EntityTeam"
    },
    "entityUser": {
        "converterClassName": "Espo\\Core\\Utils\\Database\\Orm\\LinkConverters\\EntityUser"
    },
    "entityCollaborator": {
        "converterClassName": "Espo\\Core\\Utils\\Database\\Orm\\LinkConverters\\EntityCollaborator"
    },
    "smsPhoneNumber": {
        "converterClassName": "Espo\\Core\\Utils\\Database\\Orm\\LinkConverters\\SmsPhoneNumber"
    }
}