@Override
    public Instant asTimestamp() {
      var raw = Instant.ofEpochMilli(value.longValue());
      if (value instanceof Float || value instanceof Double) {
        double doubleValue = value.doubleValue();
        raw = raw.plusNanos((long) ((doubleValue - Math.floor(doubleValue)) * Duration.ofMillis(1).toNanos()));
      }
      return raw;
    }
Returns a new list where each element of this list has been expanded to the list of elements returned by
{@code mapper}.
<p>
Individual items are treated as a list containing just that item.
planetiler-core/src/main/java/com/onthegomap/planetiler/reader/Struct.java