Specifiy both source ant target Java versions
...when compiling Java code. Since `stx:libjava` only supports Java 7,
make sure all code is compiled targeting Java 7.
![STX:LIBJAVA](
https://swing.fit.cvut.cz/projects/stx-libjava/chrome/site/javax_web_270x70.png)
*STX:LIBJAVA* is a Java Virtual Machine built into Smalltalk/X environment, allowing
Java code to be called from Smalltalk and the other way around.
- [Wiki](https://swing.fit.cvut.cz/projects/stx-libjava/wiki)
- [Issues](https://swing.fit.cvut.cz/projects/stx-libjava/report/1)
- [Jenkins CI](https://swing.fit.cvut.cz/jenkins/view/STX%20LIBJAVA/)