Do forked nodes have to be joined? UML State Diagram

Question

Do forked nodes have to be be joined in the end? And can outgoing fork nodes have guards?

Basically what I'm trying to do is return the change to the customer and continue with the car wash at the same time.

But, maybe there's a better way to do it?

Answer 1

Do forked nodes have to be be joined in the end?

For me no, this is not mandatory, but the group will end when all the flows and linked elements will end too

can outgoing fork nodes have guards?

You mean outgoing flows, the norm says a fork segment must not have Guards or Trigger

Basically what I'm trying to do is return the change to the customer and continue with the car wash at the same time.

Yes they can be done in parallel, for the wash machine point of view all is done when it return the change and the wash is done too