Default Eloqua export definitions from https://docs.oracle.com/en/cloud/saas/marketing/eloqua-develop/Developers/BulkAPI/Tutorials/ExportingActivities/Activities-export-definitions.htm

default export definitions.json

{
    "filter": "'{{Activity.Type}}'='Bounceback'",
    "name": "Bulk Activity Export - Bounceback",
    "fields": {
      "ActivityId": "{{Activity.Id}}",
      "ActivityType": "{{Activity.Type}}",
      "ActivityDate": "{{Activity.CreatedAt}}",
      "EmailAddress": "{{Activity.Field(EmailAddress)}}",
      "AssetType": "{{Activity.Asset.Type}}",
      "AssetName": "{{Activity.Asset.Name}}",
      "AssetId": "{{Activity.Asset.Id}}",
      "CampaignId": "{{Activity.Campaign.Id}}",
      "CRMCampaignId": "{{Activity.Campaign.Field(CRMCampaignId)}}",
      "CampaignName": "{{Activity.Campaign.Field(CampaignName)}}",
      "ExternalId": "{{Activity.ExternalId}}",
      "EmailRecipientId": "{{Activity.Field(EmailRecipientId)}}",
      "DeploymentId": "{{Activity.Field(EmailDeploymentId)}}",
      "SmtpErrorCode": "{{Activity.Field(SmtpErrorCode)}}",
      "SmtpStatusCode": "{{Activity.Field(SmtpStatusCode)}}",
      "SmtpMessage": "{{Activity.Field(SmtpMessage)}}"
    }
  }

{
    "filter": "'{{Activity.Type}}'='EmailClickthrough'",
    "name": "Bulk Activity Export - Email Clickthrough",
    "fields": {
      "ActivityId": "{{Activity.Id}}",
      "ActivityType": "{{Activity.Type}}",
      "ActivityDate": "{{Activity.CreatedAt}}",
      "ContactId": "{{Activity.Contact.Id}}",
      "IpAddress": "{{Activity.Field(IpAddress)}}",
      "VisitorId": "{{Activity.Visitor.Id}}",
      "VisitorExternalId": "{{Activity.Visitor.ExternalId}}",
      "EmailRecipientId": "{{Activity.Field(EmailRecipientId)}}",
      "AssetType": "{{Activity.Asset.Type}}",
      "AssetName": "{{Activity.Asset.Name}}",
      "AssetId": "{{Activity.Asset.Id}}",
      "SubjectLine": "{{Activity.Field(SubjectLine)}}",
      "EmailWebLink": "{{Activity.Field(EmailWebLink)}}",
      "EmailClickedThruLink": "{{Activity.Field(EmailClickedThruLink)}}",
      "CampaignId": "{{Activity.Campaign.Id}}",
      "CRMCampaignId": "{{Activity.Campaign.Field(CRMCampaignId)}}",
      "CampaignName": "{{Activity.Campaign.Field(CampaignName)}}",
      "ExternalId": "{{Activity.ExternalId}}",
      "DeploymentId": "{{Activity.Field(EmailDeploymentId)}}",
      "EmailSendType": "{{Activity.Field(EmailSendType)}}",
      "EmailAddress": "{{Activity.Field(EmailAddress)}}",
      "ContactIdExt": "{{Activity.Contact.Field(ContactIDExt)}}"
    }
  }

  {
    "filter": "'{{Activity.Type}}'='EmailOpen'",
    "name": "Bulk Activity Export - Email Open",
    "fields": {
      "ActivityId": "{{Activity.Id}}",
      "ActivityType": "{{Activity.Type}}",
      "ActivityDate": "{{Activity.CreatedAt}}",
      "ContactId": "{{Activity.Contact.Id}}",
      "IpAddress": "{{Activity.Field(IpAddress)}}",
      "VisitorId": "{{Activity.Visitor.Id}}",
      "VisitorExternalId": "{{Activity.Visitor.ExternalId}}",
      "EmailRecipientId": "{{Activity.Field(EmailRecipientId)}}",
      "AssetType": "{{Activity.Asset.Type}}",
      "AssetName": "{{Activity.Asset.Name}}",
      "AssetId": "{{Activity.Asset.Id}}",
      "SubjectLine": "{{Activity.Field(SubjectLine)}}",
      "EmailWebLink": "{{Activity.Field(EmailWebLink)}}",
      "CampaignId": "{{Activity.Campaign.Id}}",
      "CRMCampaignId": "{{Activity.Campaign.Field(CRMCampaignId)}}",
      "CampaignName": "{{Activity.Campaign.Field(CampaignName)}}",
      "ExternalId": "{{Activity.ExternalId}}",
      "DeploymentId": "{{Activity.Field(EmailDeploymentId)}}",
      "EmailSendType": "{{Activity.Field(EmailSendType)}}",
      "EmailAddress": "{{Activity.Field(EmailAddress)}}",
      "ContactIdExt": "{{Activity.Contact.Field(ContactIDExt)}}"
    }
  }
  {
    "filter": "'{{Activity.Type}}'='EmailSend'",
    "name": "Bulk Activity Export - Email Send",
    "fields": {
      "ActivityId": "{{Activity.Id}}",
      "ActivityType": "{{Activity.Type}}",
      "ActivityDate": "{{Activity.CreatedAt}}",
      "EmailRecipientId": "{{Activity.Field(EmailRecipientId)}}",
      "ContactId": "{{Activity.Contact.Id}}",
      "AssetType": "{{Activity.Asset.Type}}",
      "AssetName": "{{Activity.Asset.Name}}",
      "AssetId": "{{Activity.Asset.Id}}",
      "SubjectLine": "{{Activity.Field(SubjectLine)}}",
      "EmailWebLink": "{{Activity.Field(EmailWebLink)}}",
      "CampaignId": "{{Activity.Campaign.Id}}",
      "CRMCampaignId": "{{Activity.Campaign.Field(CRMCampaignId)}}",
      "CampaignName": "{{Activity.Campaign.Field(CampaignName)}}",
      "ExternalId": "{{Activity.ExternalId}}",
      "DeploymentId": "{{Activity.Field(EmailDeploymentId)}}",
      "EmailSendType": "{{Activity.Field(EmailSendType)}}",
      "EmailAddress": "{{Activity.Field(EmailAddress)}}",
      "ContactIdExt": "{{Activity.Contact.Field(ContactIDExt)}}"
    }
  }
  {
    "filter": "'{{Activity.Type}}'='FormSubmit'",
    "name": "Bulk Activity Export - Form Submit",
    "fields": {
      "ActivityId": "{{Activity.Id}}",
      "ActivityType": "{{Activity.Type}}",
      "ActivityDate": "{{Activity.CreatedAt}}",
      "ContactId": "{{Activity.Contact.Id}}",
      "VisitorId": "{{Activity.Visitor.Id}}",
      "VisitorExternalId": "{{Activity.Visitor.ExternalId}}",
      "AssetType": "{{Activity.Asset.Type}}",
      "AssetName": "{{Activity.Asset.Name}}",
      "AssetId": "{{Activity.Asset.Id}}",
      "RawData": "{{Activity.Field(RawData)}}",
      "CampaignId": "{{Activity.Campaign.Id}}",
      "CRMCampaignId": "{{Activity.Campaign.Field(CRMCampaignId)}}",
      "CampaignName": "{{Activity.Campaign.Field(CampaignName)}}",
      "ExternalId": "{{Activity.ExternalId}}",
      "EmailAddress": "{{Activity.Contact.Field(C_EmailAddress)}}",
      "ContactIdExt": "{{Activity.Contact.Field(ContactIDExt)}}"
    }
  }
  {
    "filter": "'{{Activity.Type}}'='PageView'",
    "name": "Bulk Activity Export - Page View",
    "fields": {
      "ActivityId": "{{Activity.Id}}",
      "ActivityType": "{{Activity.Type}}",
      "ActivityDate": "{{Activity.CreatedAt}}",
      "ContactId": "{{Activity.Contact.Id}}",
      "VisitorId": "{{Activity.Visitor.Id}}",
      "VisitorExternalId": "{{Activity.Visitor.ExternalId}}",
      "WebVisitId": "{{Activity.Field(WebVisitId)}}",
      "Url": "{{Activity.Field(Url)}}",
      "ReferrerUrl": "{{Activity.Field(ReferrerUrl)}}",
      "IpAddress": "{{Activity.Field(IpAddress)}}",
      "IsWebTrackingOptedIn": "{{Activity.Field(IsWebTrackingOptedIn)}}",
      "CampaignId": "{{Activity.Campaign.Id}}",
      "CRMCampaignId": "{{Activity.Campaign.Field(CRMCampaignId)}}",
      "CampaignName": "{{Activity.Campaign.Field(CampaignName)}}",
      "ExternalId": "{{Activity.ExternalId}}",
      "EmailAddress": "{{Activity.Contact.Field(C_EmailAddress)}}",
      "ContactIdExt": "{{Activity.Contact.Field(ContactIDExt)}}"
    }
  }
  {
    "filter": "'{{Activity.Type}}'='Subscribe'",
    "name": "Bulk Activity Export - Subscribe",
    "fields": {
      "ActivityId": "{{Activity.Id}}",
      "ActivityType": "{{Activity.Type}}",
      "ActivityDate": "{{Activity.CreatedAt}}",
      "EmailRecipientId": "{{Activity.Field(EmailRecipientId)}}",
      "AssetType": "{{Activity.Asset.Type}}",
      "AssetName": "{{Activity.Asset.Name}}",
      "AssetId": "{{Activity.Asset.Id}}",
      "CampaignId": "{{Activity.Campaign.Id}}",
      "CRMCampaignId": "{{Activity.Campaign.Field(CRMCampaignId)}}",
      "CampaignName": "{{Activity.Campaign.Field(CampaignName)}}",
      "ExternalId": "{{Activity.ExternalId}}",
      "EmailAddress": "{{Activity.Field(EmailAddress)}}",
      "ContactIdExt": "{{Activity.Contact.Field(ContactIDExt)}}"
    }
  }
  {
    "filter": "'{{Activity.Type}}'='Unsubscribe'",
    "name": "Bulk Activity Export - Unsubscribe",
    "fields": {
      "ActivityId": "{{Activity.Id}}",
      "ActivityType": "{{Activity.Type}}",
      "ActivityDate": "{{Activity.CreatedAt}}",
      "EmailRecipientId": "{{Activity.Field(EmailRecipientId)}}",
      "AssetType": "{{Activity.Asset.Type}}",
      "AssetName": "{{Activity.Asset.Name}}",
      "AssetId": "{{Activity.Asset.Id}}",
      "CampaignId": "{{Activity.Campaign.Id}}",
      "CRMCampaignId": "{{Activity.Campaign.Field(CRMCampaignId)}}",
      "CampaignName": "{{Activity.Campaign.Field(CampaignName)}}",
      "ExternalId": "{{Activity.ExternalId}}",
      "EmailAddress": "{{Activity.Field(EmailAddress)}}",
      "ContactIdExt": "{{Activity.Contact.Field(ContactIDExt)}}"
    }
  }
  {
    "filter": "'{{Activity.Type}}'='WebVisit'",
    "name": "Bulk Activity Export - Web Visit",
    "fields": {
      "ActivityId": "{{Activity.Id}}",
      "ActivityType": "{{Activity.Type}}",
      "ActivityDate": "{{Activity.CreatedAt}}",
      "ContactId": "{{Activity.Contact.Id}}",
      "VisitorId": "{{Activity.Visitor.Id}}",
      "VisitorExternalId": "{{Activity.Visitor.ExternalId}}",
      "ReferrerUrl": "{{Activity.Field(ReferrerUrl)}}",
      "IpAddress": "{{Activity.Field(IpAddress)}}",
      "NumberOfPages": "{{Activity.Field(NumberOfPages)}}",
      "FirstPageViewUrl": "{{Activity.Field(FirstPageViewUrl)}}",
      "Duration": "{{Activity.Field(Duration)}}",
      "ExternalId": "{{Activity.ExternalId}}",
      "EmailAddress": "{{Activity.Contact.Field(C_EmailAddress)}}",
      "ContactIdExt": "{{Activity.Contact.Field(ContactIDExt)}}"
    }
  }

You can now include Contact.Id for Bounceback, Subscribe, and Unsubscribe activity export definitions. This enhancement enables developers to include Contact.Id on export definitions for all activity types.
You can now include user fields for EmailOpen, EmailClickthrough, and EmailSend activity export definitions. One use case this enhancement enables, is allowing including sender and user attributes on email activities exported via the Bulk API, so that the activity can be properly assigned to the correct user in CRM. Discover user fields using the Retrieve a list of user fields endpoint: GET /api/Bulk/2.0/users/fields. User fields can be added with the following statement: {{Activity.User.Field()}}

https://www.oracle.com/webfolder/technetwork/tutorials/tutorial/cloud/eloqua/18D-eloqua-nfs.htm