The support team told me that opentoline was now directly called through java.
I found a way to get a similar behavior by overring the function errorDocCallback.m (in toolbox/matlab/helptools/+HelpUtils).
In this way, clicking on the filename will open the external editor at the right location.
A code like the following does the job:
editor = system_dependent('getpref', 'EditorOtherEditor');
editor = editor(2:end);
linecol = sprintf('+%d',lineNumber);
cmd=[editor ' "' linecol '" "' fileName '" &'];
system(cmd);
