build a tree of existing groups

hi Mr Anton.
I wish u the best.
I am trying to add a tree representation of defined groups "grid tree panel or tree panel".
U have a class in traccar.database named groupTree.
can i leverage from it in implementing rest service to return json tree?
can u help in an example of building tree panel in extjs with ajax proxy to make a dynamic tree?
sorry for my Qs, thanks in advance.

Done.
Group Tree Panel