Type safety Warning on `Result` class

Description
Type safety is not applied when decoding the Result class throught the JSON handler in the method getKeys() and getTasks()

        Result<Key> result = httpClient.get(urlPath, Result.class, Key.class);

        Result<Task> result = httpClient.get(urlPath, Result.class, Task.class);

This warning is thrown:
Type safety: The expression of type Result needs unchecked conversion to conform to Result<Key>Java(16777748)

Notes
This issue should be implemented before the resolution of #420

Start at the getKeys() and getTasks() entry points and inspect the JSON handler's decoding of Result.class with Key.class and Task.class. Check how the Result type is declared and how #420 affects the work; done means the unchecked conversion warning is resolved while both results remain correctly typed.