public final Geometry line() throws GeometryException {
    if (!canBeLine()) {
      throw new GeometryException("feature_not_line", "cannot be line", true);
    }
    if (linearGeometry == null) {
      linearGeometry = computeLine();
    }
    return linearGeometry;
  }
Returns this feature as a {@link LineString} or {@link MultiLineString} in world web mercator coordinates.

@throws GeometryException if an error occurs constructing the geometry, or of this feature should not be
                          interpreted as a line
planetiler-core/src/main/java/com/onthegomap/planetiler/geo/WithGeometry.java