Run openHAB with eclipse developing binding and debug it linux

i have installed openhab 2.2 on ubuntu. This works fine.
I want to develop bindings. So I installed eclipse and cloned git openHab2-addons repository from master (version 2.4.0.M4) in the directory /home/user/openhab2-master/git.
I executed file. This works fine.
Then i add a breakpoint and clicked on debug configurations. I clicked on plugins and checked everything and clicked on debug.
I get 600 errors and eclipse created many folders in my /home/user/openhab2-master/git.
I canceled the process.

Can somebody explan the build process? Should openHAB run at the same time?
What i am doing wrong?
Should i clone all repositories to run it with eclipse?