In the body of the request the following fields can be used:
projectIds (optional): This field determines which projects to backup. This field is optional, if omitted, the backup will contain Xray information of all projects containing it.
modifiedSince (optional): This field can hold a date in order for a partial backup to be generated containing only entities that were change from that date until now. This field is optional, if not supplied a full backup will be generated.
withAttachmentswithAttachment(optional): It determines if the a zip file with the attachments should also be generated.