API keys should not be hardcoded in the HubProducer class.
Should be externalized,e.g. using Maven resource filtering.
A default could be in the POM, allowing easy overriding, e.g. via a local users' ~/.m2/settings.xml. There are assumed values like "localhost", which work fine for a standalone demo, but also should be more flexible in some environments.
If more people all use the same (Agorava's) API Key, and do something "stupid", e.g. too many API calls, etc., blame will be on US (the API Key owner) so we should allow people to override that key by using their own.