SeriesServiceImpl.findFullInfoById(): add unit test for hidden images

[0pdd]

The puzzle 1356-3e6e19fa from #1356 has to be resolved:

mystamps/src/main/java/ru/mystamps/web/feature/series/SeriesServiceImpl.java

Line 224 in 01dca27

// @todo #1356 SeriesServiceImpl.findFullInfoById(): add unit test for hidden images

The puzzle was created by Slava Semushin on 04-May-20.