public int getPropertyIndex(String propertyName) {
   return dpm.getPropertyNames().indexOf(propertyName);
 }
 public boolean containsProperty(String propertyName) {
   return dpm.contains(propertyName);
 }
 public List<String> getPropertiesNames() {
   return dpm.getPropertyNames();
 }
 public int getNumberOfProperties() {
   return dpm.getPropertyNames().size();
 }