You need to refactor this class, it is a simple class that makes a call to a http API to retrieve a list of books and return them. Think about extensibility - how could you easily add other book seller APIs in the the future, handle different API formats, different query types (by publisher, by year published etc - things like that).
Refactor this to what you consider to be production ready code.
Simply fork this repository and commit and push your changes to yor fork.