Properly document nullable members or make them not nullable.

[safield]

Some classes in this library have nullable type member variables, and it is not apparent why.

For example...

/// A line
class GeoJsonLine {
  /// Default constructor
  GeoJsonLine({this.geoSerie, this.name});

  /// The geometry data
  GeoSerie? geoSerie;

  /// The name of the line
  String? name;

  /// Serialize to a geojson feature string
  String? serializeFeature(Map<String, dynamic>? properties) =>
      geoSerie?.toGeoJsonFeatureString(properties);
}

Why is GeoSerie nullable? Does a GeoJsonLine make sense without a GeoSerie? Under what circumstances would this be null? Should this even be null?

If this member is never null, it should be typed as such. Libraries should try to never expose nullable types unless there is very good reason.

[synw]

@it-sam could you comment on this please? As you did the null safety migration

[it-sam]

@synw @safield is right, @safield Would you mind updating it?