private Set<String> arrayToSet(Object[] arr){
  HashSet<String> r=new HashSet<>();
  if (null == arr)   return r;
  for (  Object o : arr) {
    if (null != o)     r.add(o.toString());
  }
  return r;
}

private Set < String > arrayToSet ( Object [ ] arr ) { HashSet < String > r = new HashSet < > ( ) ; if ( null == arr ) return r ; for ( Object o : arr ) { if ( null != o ) r . add ( o . toString ( ) ) ; } return r ; }
take an array of any type and generate a set containing the tostring . set is guarantee to never be null ( but may be empty )
