code: public boolean hasCollectionProperty( Property propertyId ) {
          Object value = getProperty(propertyId);
          return (value instanceof Collection<?> && !((Collection<?>)value).isEmpty());
      }
docs: Indicates if there is a non-null and non-empty Collection value for the property.
  
  @param propertyId the property identifier
  @return true if this node has value for the supplied property and that value is a non-empty Collection