Return dashboard_url in polling last operation of service instance

[leonwanghui]

Background

Currently for provision request, the service broker will return dashboard_url field in the response body.

Problem

For aync operation, some brokers can't return the dashboard_url value in time, but in PollLastOperation request there is no field that indicates the required dashboard_url value, so this may cause some issues that the platform could not get the dashboard_url info and pass it to users.

Goal

Add dashboard_url field definition in response body of poll last operation, so that the platform can get the info of dashboard_url when brokers finish provisioning operation.

[jmrodri]

This is EXACTLY the issue I wanted to talk about. I can take ownership of this one.

[duglin]

Assigned to @leon but Jesus will help

[leonwanghui]

Thanks @jmrodri and @duglin

[mattmcneeney]

The dashboard_url can now be fetched via the Fetching a Service Instance endpoint, so closing this!

[gberche-orange]

@mattmcneeney The GET /v2/service_instances/:instance_id dashboard_url response field mentions

Note: a Service Broker that wishes to return dashboard_url for a Service Instance MUST return it with the initial response to the provision request, even if the service is provisioned asynchronously.

Should we read it is valid for a broker to return a different value of the dashboard_url between the initial response to the provision request, and the GET /v2/service_instances/:instance_id response ?