LTI 1.3 Deeplinking accept_presentation_document_targets

Hi! i have tool that implements LTI 1.3 and it is able to connect to several Platforms without problem. A few months ago, i started seeing  that the JWT for Deeplinkign requests from one of my customer were comming with the accept_presentation_document_targets as empty 


{
"deep_link_return_url": "https://lti-service.svc.schoology.com/lti-service/deep-linking-return",
"accept_types": [
"file"
],
"accept_presentation_document_targets": [],
"accept_media_types": "text/html",
"accept_multiple": true,
"data": "27c89946-5d35-4122-8f36-a50d3b99cf0d"
}
}


My tool is rejecting this kind of requests because this property needs at leats one possible value but I am not sure about this. Documentation say that this field is required but that can also means the the field can be empty. I would like to know if empty is a valid value and i should fix this.

Thanks