JUnit does not run with JDK5 because it is compiled with JDK 6

[Vladimir Korenev]

JUnit in Intrepid is compiled with JDK 6. It fails to run with JDK 5, which is included in Intrepid too.
Steps to reproduce:
1. Make java-1.5.0-sun JDK active.
2. Execute java -cp /usr/share/java/junit-3.8.2.jar junit.swingui.TestRunner.
The result is:
Exception in thread "main" java.lang.UnsupportedClassVersionError: Bad version number in .class file
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:620)
        at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:124)
        at java.net.URLClassLoader.defineClass(URLClassLoader.java:260)
        at java.net.URLClassLoader.access$100(URLClassLoader.java:56)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:195)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:268)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:251)
        at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319)

[marcelnijman (marcel-marcelnijman-deactivatedaccount)]

The strange thing is that the original source can be compiled with java 1.4.2.
So why does the version in Interped enforce java 6?

http://ftp.de.debian.org/debian/pool/main/j/junit/junit_3.8.2.orig.tar.gz

[Emmanuel Bourg (ebourg)]

Java 9 is no longer able to generate Java 5 compatible bytecode and it'll be worse with every new Java release according to JEP 182. This means every time this package is rebuilt the runtime requirement becomes higher than previously. There is nothing we can do since we don't keep old compilers.