abe1832128
This commit updates some code introduced by I977a77286f to improve its readability and also honor some java best practices, e.g.: * explicitly prohibit inheritance if a class isn't intended for that (Effective Java Item 19's advice: design and document for inheritance or else prohibit it). * Write unit tests in three sections, aka "arrange", "act", "assert". Change-Id: I8939370f16c2465c7ba102afd3877a31babd0c89