code: public static ImmutableMultimap<String, String> loadStringMultimap(CharSource multimapSource)
        throws IOException {
      final ImmutableMultimap.Builder<String, String> ret = ImmutableMultimap.builder();
  
      int count = 0;
      for (final String line : multimapSource.readLines()) {
        ++count;
        if (isCommentLine(line)) {
          continue;
        }
        final List<String> parts = multimapSplitter.splitToList(line);
        if (parts.isEmpty()) {
          continue;
        }
        ret.putAll(parts.get(0), skip(parts, 1));
      }
  
      return ret.build();
    }
docs: Loads a file in the format {@code key value1 value2 value3} (tab-separated) into a {@link
  com.google.common.collect.Multimap} of {@code String} to {@code String}. Each key should only
  appear on one line, and there should be no duplicate values. Each key and value has whitespace
  trimmed off. Skips empty lines and allows comment-lines with {@code #} in the first position.
  If a key has no values, it will not show up in the keySet of the returned multimap.