private Map<String, Object> buildTags(int num, IntUnaryOperator key, IntUnaryOperator value) {
    if (num > 0) {
      Map<String, Object> tags = HashMap.newHashMap(num);
      for (int i = 0; i < num; i++) {
        String k = fieldDecoder.decodeString(key.applyAsInt(i));
        String v = fieldDecoder.decodeString(value.applyAsInt(i));
        tags.put(k, v);
      }
      return tags;
    }
    return Collections.emptyMap();
  }
Decompresses and parses a header block of an OSM input file.
planetiler-core/src/main/java/com/onthegomap/planetiler/reader/osm/PbfDecoder.java