I'm investigating transactions using Parity trace which provides useful data over a transaction flow. Among this data is the
Subtraces field which allows me to understand how many sub-calls each action has.
When delegate-call is used it seems that the subtraces are a bit confusing.
For example, looking at this transaction trace I can see a few delegate calls, for example
Action  which has 1 subtrace, but I can't see any action called by this step (by
0x2157a7894439191e520825fe9399ab8655e0f708 in this case).
Why is that? What is the meaning of the subtraces field in calls of type delegatecall?