private static void addSuppressed(Throwable exception,Throwable suppressed){
  if (exception != null && suppressed != null) {
    exception.addSuppressed(suppressed);
  }
}

private static void addSuppressed ( Throwable exception , Throwable suppressed ) { if ( exception != null && suppressed != null ) { exception . addSuppressed ( suppressed ) ; } }
adds a throwable to the list of suppressed exceptions of the first throwable
