Update src/main/java/schueler/Entity.java, src/main/java/schueler/App.java,...
Update src/main/java/schueler/Entity.java, src/main/java/schueler/App.java, src/main/java/schueler/Priority.java, src/main/java/schueler/Project.java, src/main/java/schueler/Task.java