message: Cross reference other entities and Remove redundant Collections
diff: "200": {
  "description": "Lists a collection of user entities associated with the group.",
  "schema": {
  - "$ref": "#/definitions/UserCollection"
  + "$ref": "./apimusers.json#/definitions/UserCollection"
  }
  },
  "default": {
  "x-ms-pageable": {
  "nextLinkName": "nextLink"
  },
  - "x-ms-odata": "#/definitions/UserContract"
  + "x-ms-odata": "./apimusers.json#/definitions/UserContract"
  }
  },
  "/subscriptions/{subscriptionId}/resourceGroups/{resourceGroupName}/providers/Microsoft.ApiManagement/service/{serviceName}/groups/{groupId}/users/{uid}": {
  }
  },
  "description": "Parameters supplied to the Update Group operation."
  - },
  - "UserCollection": {
  - "properties": {
  - "value": {
  - "type": "array",
  - "items": {
  - "$ref": "#/definitions/UserContract"
  - },
  - "description": "Page values."
  - },
  - "count": {
  - "type": "integer",
  - "format": "int64",
  - "description": "Total record count number across all pages."
  - },
  - "nextLink": {
  - "type": "string",
  - "description": "Next page link if any."
  - }
  - },
  - "description": "Paged Users list representation."
  - },
  - "UserContract": {
  - "properties": {
  - "id": {
  - "type": "string",
  - "description": "User identifier path."
  - },
  - "firstName": {
  - "type": "string",
  - "description": "First name."
  - },
  - "lastName": {
  - "type": "string",
  - "description": "Last name."
  - },
  - "email": {
  - "type": "string",
  - "description": "Email address."
  - },
  - "state": {
  - "type": "string",
  - "description": "User state.",
  - "enum": [
  - "Active",
  - "Blocked"
  - ],
  - "x-ms-enum": {
  - "name": "UserStateContract",
  - "modelAsString": false
  - }
  - },
  - "registrationDate": {
  - "type": "string",
  - "format": "date-time",
  - "description": "Date of user registration. The date conforms to the following format: `yyyy-MM-ddTHH:mm:ssZ` as specified by the ISO 8601 standard.\n"
  - },
  - "note": {
  - "type": "string",
  - "description": "Administrator's note about given user."
  - },
  - "identities": {
  - "readOnly": true,
  - "type": "array",
  - "items": {
  - "$ref": "#/definitions/UserIdentityContract"
  - },
  - "description": "Collection of user identities."
  - }
  - },
  - "description": "User profile."
  - },
  - "UserIdentityContract": {
  - "properties": {
  - "provider": {
  - "type": "string",
  - "description": "Identity provider name."
  - },
  - "id": {
  - "type": "string",
  - "description": "Identifier value within provider."
  - }
  - },
  - "description": "User identity details."
  }
  },
  "parameters": {
  