public void addPart(int index,PduPart part){
  if (null == part) {
    throw new NullPointerException();
  }
  putPartToMaps(part);
  mParts.add(index,part);
}

public void addPart ( int index , PduPart part ) { if ( null == part ) { throw new NullPointerException ( ) ; } putPartToMaps ( part ) ; mParts . add ( index , part ) ; }
inserts the specified part at the specified position .
