private static HttpData httpData(String str) {
        final ByteBuf buf = UnpooledByteBufAllocator.DEFAULT.buffer(str.length());
        buf.writeCharSequence(str, Charsets.UTF_8);
        byteBufs.add(buf);
        return HttpData.wrap(buf);
    }
A test for the {@link SignalQueue} in {@link DefaultStreamMessageDuplicator}.
Queue expansion behaves differently when odd/even number head wrap-around happens.
core/src/test/java/com/linecorp/armeria/common/stream/StreamMessageDuplicatorTest.java