### Question:
OpenFrame extends DefaultByteBufHolder implements Frame { @Override public String toString() { return StringUtil.simpleClassName(this) + "[o]"; } OpenFrame(); @Override String toString(); @Override OpenFrame copy(); @Override OpenFrame duplicate(); @Override OpenFrame retain(); @Override OpenFrame retain(int increment);  }### Answer:
@Test public void content() { assertThat(new OpenFrame().content().toString(CharsetUtil.UTF_8), equalTo("o")); }