Defining Array of Objects in Swagger Documentation - ruby-on-rails

Question

I'm using swagger for quite a bit now, we have started documenting our code using it, in one place there's an API response which returns multiple objects in the included block.
Example:
{
"data": {
"id": "1",
"type": "schoolPositions",
"attributes": {
"description": "teases the students",
"mustHaves": "principle"
},
"relationships": {
"schoolLocation": {
"data": {
"id": "72",
"type": "schoolLocations"
}
},
"schoolCompensation": {
"data": {
"id": "75",
"type": "schoolCompensations"
}
},
"jobSpecs": {
"data": [
{
"id": "82",
"type": "schoolAttachments"
}
]
}
}
},
"included": [
{
"id": "72",
"type": "schoolLocations",
"attributes": {
"city": "Berhampore",
"state": "West Bengal",
"postalCode": "742101",
"country": "India",
"globalRegionId": 30,
"regionId": 683
}
},
{
"id": "75",
"type": "schoolCompensations",
"attributes": {
"salary": "",
"bonus": "",
"equity": "",
"currencyId": null,
"equityType": "percent",
"salaryDescription": null
}
},
{
"id": "82",
"type": "schoolAttachments",
"attributes": {
"attachmentType": "JobSpecificationAttachmentType",
"fileFileName": "vs.jpg",
"fileContentType": "image/jpeg",
"fileFileSize": 2410039,
"fileUpdatedAt": "2018-12-12T07:06:38Z",
"downloadUrl": "001-vs.jpg?1544598398",
"klass": "SchoolAttachments"
}
}
]
I have wasted an entire day on the internet and documentation trying to document the included part, but I'm going wrong somewhere
response 200 do
key :description, 'School Data'
schema do
property :data do
key :type, :array
items do
key :'$ref', :School
end
end
property :included do
key :type, :array
items do
key :'$ref', :SchoolLocations
key :'$ref', :SchoolCompensations
key :'$ref', :SchoolAttachments
end
end
end
end
This shows only the SchoolAttachments in the included part.
I have tried using allOff but it doesn't work.