int hashList(Iterable<Object> args)

Combine the hashCodes of an arbitrary number of values from an Iterable into one value. This function will return the same value if given "null" as if given an empty list.

Source 

int hashList(Iterable<Object> args) {
  int result = 0;
  if (args != null) {
    for (Object arg in args)
      result = _Jenkins.combine(result, arg);
  }
  return _Jenkins.finish(result);
}