Not showing which methods have covariant return type overrides hides some information from the user. For example, java.nio.MappedByteBuffer has some covariant return type overrides such as

    /**
     * {@inheritDoc}
     */
    @Override
    public final MappedByteBuffer reset() {
        super.reset();
        return this;
    }

but reset(), et. al., show up under "Methods declared in class java.nio.Buffer". The hierarchy is MappedByteBuffer extends ByteBuffer extends Buffer extends Object.