Not able to create service instance if source in the request body passed as empty or "xxx".

Request details:

POST: http://<SO-VM-IP>:8080/ecomp/mso/infra/serviceInstances/v3

BODY:
{
"requestDetails": {
"modelInfo": {
"modelType": "service",
"modelInvariantId": "1de901ed-17af-4b03-bc1f-41659cfa27cb",
"modelVersionId": "ace39141-09ec-4068-b06d-ac6b23bdc6e0",
"modelName": "demoVLB",
"modelVersion": "1.0"
},
"cloudConfiguration" : {
"lcpCloudRegionId": "RegionOne",
"tenantId": "onap"
},
"subscriberInfo": {
"globalSubscriberId": "Demonstration",
"subscriberName": "Demonstration"
},
"requestInfo": {
"instanceName": "sample-instance-2",
"source": "",                // able to create service only with source as "VID"
"suppressRollback": "false"
},
"requestParameters": {
"subscriptionServiceType": "vLB"
}
}
}