+ "a packet beginning or end message: "
+ "a default clock snapshot is needed, but none was provided: "
+ "%![stream-]+s, %![sc-]+S, with-cs=%d, "
+ "cs-val=%" PRIu64,
+ stream, stream_class, with_cs, raw_value);
+ BT_ASSERT_PRE(!need_cs ? !with_cs : true,
+ "Unexpected stream class configuration when creating "
+ "a packet beginning or end message: "
+ "no default clock snapshot is needed, but one was provided: "