return negative exit code on directory vaidation

History.md

@@ -1,3 +1,4 @@
+- return error code not only on validation but also on recursive directory validation
 - allow Bank credentials without BIC
 - allow minimum profile without delivery date
 - allow prepaid amount in invoice class

Mustang-CLI/src/main/java/org/mustangproject/commandline/Main.java

@@ -468,9 +468,11 @@ public class Main {
 		String totalResult="valid";
 		if (!zfWalk.getResult()) {
 			totalResult="invalid";
+			System.exit(-1);
 		}
 
 		System.out.println("Overall test result: "+totalResult);
+
 		return true;
 	}