public final Geometry lineMidpoint() throws GeometryException {
    if (innermostPoint == null) {
      innermostPoint = pointAlongLine(0.5);
    }
    return innermostPoint;
  }
Returns the midpoint of this line, or the longest segment if it is a multilinestring.
planetiler-core/src/main/java/com/onthegomap/planetiler/geo/WithGeometry.java