Method getQueuesNamesForAnExchange in the RabbitmqPlugin makes the first call to RabbitMQ endpoint BEFORE the vhost variable is set. The call results in an error.

Since the call to update extractors info is scheduled every several minutes, the consequent calls are made after vhost is already set, hence return meaningful results. This explains why the bug was easy to overlook.

In RabbitmqPlugin, have to make sure vhost variable is set before making the call to the endpoint.