JSON retrieval

[stklcode]

The Connector interface should provide a method for retrieval of secrets mapped as JSON object. Simple code, as Jackson is already present

Suggestion for a generic API :

public <T> T readSecretJson(final String key, final Class<T> type);

[stklcode]

I decided not to expand the Interface, but to add a second getter to the SecretResponse model to parse the response into a JSON serializable object of choice:

public <T> T getValue(Class<T> type);