for gradle now one could do:
gradle clean build -x test -x javaDoc -PjavacRelease=17
for maven something like this works to build a different target binary:
mvn clean package -Dmaven.test.skip=true -Dmaven.javadoc.skip=true -Dmaven.compiler.release=17
javac since java9 has a new flat --release to build a binary which can be run
with an older java. the public API of that older release must be followed as
well.
the flags used before, -source, -target do not do this. therefor it got
unnoticed that plantuml did not compile and run in java7 any more, despite
beeing compiled for for java7.
https://github.com/plantuml/plantuml/issues/898
project uses 2 spaces indent, lf as line ending, utf-8. make it easier
to follow this rule by adding a .editorconfig file which vscode and
intellij respect out of the box.
