Provides a list of the authenticated user's contacts. The request returns a 400 error if
`personFields` is not specified. The request returns a 410 error if `sync_token` is specified and
is expired. Sync tokens expire after 7 days to prevent data drift between clients and the server.
To handle a sync token expired error, a request should be sent without `sync_token` to get all
contacts.
Create a request for the method "connections.list".
This request holds the parameters needed by the people server. After setting any optional
parameters, call the
AbstractGoogleClientRequest.execute() method to invoke the remote operation.