TreeLine | an information storage program

I am struggling to read message off the destination channel the cloud streaming handler is being written to.

I have the gcp emulator for pub/sub running in test containers. I am able to successfully send messages to the input queue/topic(sorry I come from a JMS background, not sure which the correct term is for gcp pub/sub)

spring streaming config:

I'm new in ReactJS, but already got some problem I cannot resolve...

I have React component called Tree. This component must receive array of some data. Every element in this array must be rendered as a special child component called Department.

At the beginning, Tree has state {departments: []}, so, tree must be empty and it is. But then I change Tree's state, I set new array at departments, I see no child elements.

And the point is, that tree's state really updates, and function "render" is really called, and when I run thru departments, I get the right number of iterations in my cycle (checked with console.log). But still no child element appears.

My code works, I tried to render tree component with fixed departments and set this state in the constructor as initial state. Tree and child components worked fine.

So, I cannot imagine, what might be wrong.

Here is my code, my class Tree