I've contributed a few patches to JDT Core and UI in the past couple of years, so I'm guessing I fit in the "new contributors" category and may be able to provide some insight.
My first contribution was fixing bug 424214 and I faced two problems related to this discussion:
* I struggled to write new unit tests. At the time, I had never used JUnit 3 (which is understandable given that JUnit 4 was released early 2006). I was probably trying to write a test method with a different naming convention and it wasn't being picked up by the framework - no longer sure at this point. And as JUnit 3 was not a thing I had used, I didn't even realise it was JUnit 3 (in my mind it was some bespoke Eclipse test utility running) and consequently I couldn't easily look up any documentation to solve my problems. In the end, I ended up putting the tests in an existing file and copy-pasted as much possible, not really understanding how things fitted together. For anyone who has started writing Java in the past decade or so, these mass migrations to JUnit 4, even though they touch a lot of files and introduce commit noise, are useful.
* I struggled to get the contribution under 1000 lines to avoid the CQ. The files I changed had not been cleaned up nor touched in years, therefore some of the automatic save actions had introduced additional diffs, for example import ordering. With Till Brichy's help I then had to revert some of these automatic changes, just for the sake of getting under the 1000 line limit in time for the M3 deadline. Note that this was my very first usage of Gerrit, so reverting lines and pushing new patch sets was not as straightforward for me as it would be now. "Fighting" against save actions would not have been needed had the files been cleaned up prior to my contribution.
Admittedly, these are only two small inconveniences which some of you may even consider as anecdotal, but hopefully they do illustrate cases where mass cleanups can help newcomers. :)
Best regards,
Pierre-Yves
