usagedata object

{
  /* set by upodi */
  "id": "guid",
  "amount": "decimal",
  /* The date-time of the usage to be used in the calculation. */
  "entrydate": "datetime",
  /* ReferenceID grouping together UsageData relating to the same ProductPlanCharge and 			Subscription. */
  "referenceid": "guid",
  /* custom key, example a remote id */
  "refkey": "string", 
  /* The subscriptionCharge the UsageData is related to. */
  "subscriptionchargeid": "guid",
  /* set by upodi */
  "createdby": "guid",
  /* set by upodi */
  "modifiedby": "guid",
  /* set by upodi */
  "createddate": "datetime",
  /* set by upodi */
  "modifieddate": "datetime"
}