minor: getting rid of warning

SVN: 23018

openbis/source/java/ch/systemsx/cisd/openbis/generic/client/web/client/application/ui/field/ParameterField.java

@@ -293,6 +293,7 @@ public class ParameterField extends TriggerField<ModelData> implements IParamete
             return new ParameterWithValue(parameterName, getRawValue());
         }
 
+        @Override
         public Field<?> asWidget()
         {
             return this;