<init>

Base class for all futures that get something. Get one element.

In the subclasses, you will get easy semantics.

• onGet is called when a successful response has been received (not null)
• onNotFound is called, when a response has been received, but the answer is null, indicating that the searched key was not found

The subclasses differ by these orthogonal concepts:

• Do you get one or multiple things? Multiple things have the suffix All
• In your method, do you transform the response from the DHT before you return it? Transformed responses have the suffix Custom
• E.g., you get a UserId from the DHT, but you want to return a User