UI doesn't show a Google Calendar step

When I want to create an integration with Google Calendar connector, the Google calendar step is not shown. Instead of that, "Something is wrong" is shown with the message "Error: Bad Request". In the server pod is not any related error.
The browser console contains request on

https://syndesis.my-minishift.syndesis.io/api/v1/connections/i-Lsvro4u43sjVeDtm7RAz/actions/io.syndesis:google-calendar-receive-events-connector

which returns status 400.

When I go to the Google Calendar connection and click on Validate, show only error warning with "Connection couln't be verified: e is null". The error message should be more meaningful.

When I look to the browser console, there is a request on

https://syndesis.my-minishift.syndesis.io/api/v1/connectors/google-calendar/verifier

which returns 500 status code with response

{
    "developerMsg":"com.google.api.client.googleapis.services.json.AbstractGoogleJsonClient$Builder.setBatchPath(Ljava/lang/String;)Lcom/google/api/client/googleapis/services/AbstractGoogleClient$Builder;",
    "errorCode":500,
    "userMsg":"com.google.api.client.googleapis.services.json.AbstractGoogleJsonClient$Builder.setBatchPath(Ljava/lang/String;)Lcom/google/api/client/googleapis/services/AbstractGoogleClient$Builder;"
}

When I do Reconnect, UI shows "Connection successful" however the Validate doesn't work either.