private static String doubleToString(Double d) {
    return d % 1 == 0 ? Long.toString(d.longValue()) : d.toString();
  }
Attempts to coerce {@code in} to an instance {@code out} using the first registered conversion functions that
applies.

@throws IllegalArgumentException if there is no available conversion
planetiler-custommap/src/main/java/com/onthegomap/planetiler/custommap/TypeConversion.java