private void ensureEntryArrayMutable(){
  checkMutable();
  if (entryList.isEmpty() && !(entryList instanceof ArrayList)) {
    entryList=new ArrayList<Entry>(maxArraySize);
  }
}

private void ensureEntryArrayMutable ( ) { checkMutable ( ) ; if ( entryList . isEmpty ( ) && ! ( entryList instanceof ArrayList ) ) { entryList = new ArrayList < Entry > ( maxArraySize ) ; } }
lazily creates the entry list . any code that adds to the list must first call this method .
