API Management SchemaContractProperties Document is not to its swagger definition

[yupwei68]

Bug Report

• import path of package in question, e.g. .../services/compute/mgmt/2018-06-01/compute
  "github.com/Azure/azure-sdk-for-go/services/preview/apimanagement/mgmt/2021-01-01-preview/apimanagement"

• SDK version e.g. master, latest, 18.1.0
  "55.5.0"

• Specify the exact commit if possible; one way to get this is the REVISION
  column output by dep status "github.com/Azure/azure-sdk-for-go.

• output of go version

• What happened?
  The go sdk data struct for Document is not according to its swagger definition

swagger link:
https://github.com/Azure/azure-rest-api-specs/blob/master/specification/apimanagement/resource-manager/Microsoft.ApiManagement/preview/2021-01-01-preview/definitions.json#L4971

SDK link:
https://github.com/Azure/azure-sdk-for-go/blob/main/services/preview/apimanagement/mgmt/2021-01-01-preview/apimanagement/models.go#L12690

• What did you expect or want to happen?
  The go sdk data struct for Document is according to its swagger definition
• How can we reproduce it?
• Anything we should know about your environment.

[ArcturusZhang]

Since the swagger has changed on the master branch, the generated code is aligned with the swagger. Therefore closing this issue.
Thank you!