Many applications and libraries distributed by Debian are written in the Java programming language. In fact based on simply counting source code lines, it is ranked in third place only after C and C++. The Java team alone maintains more than one thousand source packages ranging from web servers to IDEs. Packaging Java software can be difficult at times because all packages must be built from source but no internet connections are allowed at build time. None of the packages in the main archive area may require software outside of that area to function thus we have to package every dependency and make sure it complies with the Debian Free Software Guidelines. This is often completely diametral how Java developers usually build software (versioned dependencies downloaded from online repositories like Maven Central). And if you know that Debian prefers to ship only one software version because of security support but different applications tend to depend on different versions at the same time and we also strive for one long-term supported Java Virtual Machine, the possible problems are easily imaginable. Last but not least Java development has become rapider in the past with new OpenJDK versions and bugs every six months. How this all works or not will be told during the next 15 minutes.