Style: Make isValidator() of AbstractCheck final

CityDoctorParent/CityDoctorModel/src/main/java/de/hft/stuttgart/citydoctor2/check/AbstractCheck.java

@@ -53,7 +53,7 @@ public abstract class AbstractCheck extends Check {
 	}
 
 	@Override
-	public boolean isValidator() {
+	public final boolean isValidator() {
 		return false;
 	}