@Override
    public ByteBuffer nioBuffer() {
        return nioBuffer(readerIndex, readableBytes());
    }
@Test
    public void testNioBufferAfterRelease() {
        assertThrows(IllegalReferenceCountException.class, new Executable() {
            @Override
            public void execute() {
                releasedBuffer().nioBuffer();
            }
        });
    }