at install-time:
- first, without -javadir it just won't work ; then, it is reported in the easybuild log in the next 30 lines after:
  `main.fileTools INFO cmd "export _JAVA_OPTIONS="-Xmx512m"; ./install -v -inputFile`

at run-time:
- it will use its own jre no matter what (reported in the first four lines of `ver`)