minor: - Remove warning.

SVN: 6642

bds/source/java/ch/systemsx/cisd/bds/check/ProblemReport.java

@@ -38,6 +38,7 @@ public class ProblemReport
             this.severity = level;
         }
 
+        @Override
         public String toString()
         {
             if (Severity.ERROR.equals(this.severity))