docs: public void undo() {
  
          if (hasUndo()) {
              ChangeType type = m_current.getType();
              String entityId = m_current.getEntityId();
              String attributeName = m_current.getAttributeName();
              int valueIndex = m_current.getValueIndex();
              m_redo.push(m_current);
              m_current = m_undo.pop();
              changeEntityContentValues(m_current.getEntityData(), entityId, attributeName, valueIndex, type);
              fireStateChange();
          }
      }