code: private List<String> splitToList(String input)
    {
      Preconditions.checkNotNull(input);
  
      Iterator<String> iterator = splitter.split(input).iterator();
      List<String> result = new ArrayList<String>();
  
      while (iterator.hasNext()) {
        result.add(iterator.next());
      }
  
      return Collections.unmodifiableList(result);
    }
docs: Copied from Guava's {@link Splitter#splitToList(CharSequence)}.
  This is to avoid the error of the missing method signature when using an old Guava library.
  For example, it may happen when running Druid Hadoop indexing jobs, since we may inherit the version provided by
  the Hadoop cluster. See https://github.com/apache/incubator-druid/issues/6801.