Improve indentation in TocTreeBuilder.java (lambda arguments) to fix Checkstyle ci

Michael Hamann Vincent Massol 

The Checkstyle CI failure is caused by a fix for a false negative in Indentation. Checkstyle silently skipped indentation validation on arrow lambda body continuation lines, that's what the PR is addressing. 

> However, to me the proposed indentation change looks super weird, I don't understand why line 261 should stay that deeply indented. 
It shouldn't be (if user chooses strict indentation, then it shouldn't be flagged). That's likely a false negative, since there is less coverage for arrow lambda expressions in particular 

> The current indentation in that line matches what our IntelliJ code style produces

I understand your concern. We have a project active for this "Reconcile formatters of Eclipse , NetBeans and IntelliJ IDEA IDEs by Checkstyle config". The main deal right now is that we need to do a deep refactor for indentation and maybe different IDE configurations sync, this would ensure that even if people are using a different IDE, code formatting stays synced throughout team.