docs: public static void addExtendedProperty(String propName, String dataType, boolean multiValued, Object defaultValue) {
          if (dataType == null || "null".equalsIgnoreCase(dataType))
              return;
  
          if (extendedPropertiesDataType.containsKey(propName)) {
              Tr.warning(tc, WIMMessageKey.DUPLICATE_PROPERTY_EXTENDED, new Object[] { propName, "PersonAccount" });
              return;
          }
  
          if (getPropertyNames("PersonAccount").contains(propName)) {
              Tr.warning(tc, WIMMessageKey.DUPLICATE_PROPERTY_ENTITY, new Object[] { propName, "PersonAccount" });
              return;
          }
  
          extendedPropertiesDataType.put(propName, dataType);
          if (defaultValue != null)
              extendedPropertiesDefaultValue.put(propName, defaultValue);
          if (multiValued)
              extendedMultiValuedProperties.add(propName);
      }