DRAFT
Observed
ConcreteClassOnlyImplementDirectAbstract
Incorrect
A concrete class only needs to implement abstract methods declared in its direct supertypes
Correct
A concrete class needs to implement all abstract methods declared in its supertypes, both direct and indirect
CorrectionHere is what's right.
Here is what's right.
It has to implement all abstract methods declared in any of its supertypes, even if they are declared in a supertype of a supertype (e.g., declared in an interface that is extended by the interface the concrete class implements).