Checking core structure...
compile_project:10: no matches found: *.in
rm -f calc-core.jar `find . -name \*.class`
(cd src; javac -encoding UTF-8 `find . -name \*.java`)
./calc/ValidityMenu.java:3: error: package ist.po.ui does not exist (cannot be used in the core project)
import ist.po.ui.ValidityPredicate;
                ^
./calc/ValidityMenu.java:5: error: cannot find symbol
public class ValidityMenu extends ValidityPredicate<Manager>{
                                  ^
  symbol: class ValidityPredicate
./calc/ValidityMenu.java:17: error: cannot find symbol
		return _receiver.isValid();
		       ^
  symbol:   variable _receiver
  location: class ValidityMenu
./calc/ValidityMenu.java:14: error: method does not override or implement a method from a supertype
	@Override
	^
4 errors
make: *** [all] Error 1