@Override
    final void cleanupObjects(@Nullable Throwable cause) {
        if (obj != null) {
            StreamMessageUtil.closeOrAbort(obj, cause);
            obj = null;
        }
    }
A {@link FixedStreamMessage} that only publishes one object.
core/src/main/java/com/linecorp/armeria/internal/common/stream/OneElementFixedStreamMessage.java