Dashboard update fails with constraint violations

[nicr9]

Describe the bug
dt.dashboards.put(...) fails with errors claiming that the tiles and dashboardMetadata fields can't be null

To Reproduce

for dashboard in dt.dashboards.list():
    body = dashboard.get_full_dashboard().json()
    body['dashboardMetadata']['owner'] = new_owner

    resp = dt.dashboards.put(dashboard.id, body)

See error:

Traceback (most recent call last):
  File "dashboard-demo.py", line 38, in <module>
    resp = dt.dashboards.put(dashboard.id, body)
  File "/usr/lib/python3.6/site-packages/dynatrace/configuration_v1/dashboard.py", line 53, in put
    return self.__http_client.make_request(f"/api/config/v1/dashboards/{dashboard_id}", params=params, method="PUT")
  File "/usr/lib/python3.6/site-packages/dynatrace/http_client.py", line 146, in make_request
    raise Exception(f"Error making request to {url}: {r}. Response: {r.text}")
Exception: Error making request to https://abc123.live.dynatrace.com/api/config/v1/dashboards/xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx: <Response [400]>. Response: {"error":{"code":400,"message":"Constraints violated.","constraintViolations":[{"path":"dashboardMetadata","message":"may not be null","parameterLocation":"PAYLOAD_BODY","location":null},{"path":"tiles","message":"Tiles configuration is invalid.","parameterLocation":"PAYLOAD_BODY","location":null},{"path":"tiles","message":"may not be null","parameterLocation":"PAYLOAD_BODY","location":null}]}}

Expected behavior

Response should be a 204

Desktop (please complete the following information):

• OS: RHEL 7
• python: 3.6.8
• dt: 1.1.73 (installed via pip)