public void addAttachments(Collection<File> files){
  if (files == null || files.size() == 0)   return;
  for (  File f : files) {
    addAttachment(f);
  }
}

public void addAttachments ( Collection < File > files ) { if ( files == null || files . size ( ) == 0 ) return ; for ( File f : files ) { addAttachment ( f ) ; } }
add a collection of attachments
