public String decode(int id) {
    String str = idToString[id];
    if (str == null) {
      throw new IllegalArgumentException("No string for " + id);
    }
    return str;
  }
Returns the string for {@code id}.

@throws IllegalArgumentException if there is no value for {@code id}.
planetiler-core/src/main/java/com/onthegomap/planetiler/util/CommonStringEncoder.java