Based on official documentation:
In order to add your launcher to the Unity Launcher on the left, you select and drag it onto the Launcher panel. Alternatively, you can place your .desktop file at /usr/share/applications/ or at ~/.local/share/applications/. After moving your file there, search for it in the Dash (Windows key -> type the name of the application) and drag and drop it to the Unity Launcher. Now your launcher (.desktop file) is locked on the Unity Launcher!
It means, that you can add a launcher manually via "drag and drop". But, is it possible to do this programatically?
I can explain why I am asking about it:
I have my own scpirt, it downloads the latest version of Eclipse IDE, creates eclipse.desktop file without iteraction with User.
And on the last step I want to add Eclipse.desktop file to Unity Launcher and I do not want to ask user to do it.
I analized the spesification for *.desktop files and did get an answer.
Please provide advice.