public Object groupChange(String groupColumnName,Object value){
  if (!isGroupColumn(groupColumnName))   return null;
  Object newValue=value;
  if (newValue == null)   newValue=NULL;
  if (m_groupMap.containsKey(groupColumnName)) {
    Object oldValue=m_groupMap.get(groupColumnName);
    if (newValue.equals(oldValue))     return null;
    m_groupMap.put(groupColumnName,newValue);
    return oldValue;
  }
  m_groupMap.put(groupColumnName,newValue);
  return null;
}

public Object groupChange ( String groupColumnName , Object value ) { if ( ! isGroupColumn ( groupColumnName ) ) return null ; Object newValue = value ; if ( newValue == null ) newValue = NULL ; if ( m_groupMap . containsKey ( groupColumnName ) ) { Object oldValue = m_groupMap . get ( groupColumnName ) ; if ( newValue . equals ( oldValue ) ) return null ; m_groupMap . put ( groupColumnName , newValue ) ; return oldValue ; } m_groupMap . put ( groupColumnName , newValue ) ; return null ; }
check for group change
