Nullability of Feature properties

[tobrun]

Reposting from issue downstream in mapbox/mapbox-gl-native#12744:

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Have not actually experienced any problems, but the code shows how it could happen.

In com.mapbox.geojson.Feature the properties method is annotated as Nullable. The getStringProperty and others like it deferences the returned value with out checking for null.

Android versions: N/A
Device models: N/A
Mapbox SDK versions: 6.4.0

[osana]

This is related to #813

According to GeoJson spec properties must have @nullable annotation:
A Feature object has a member with the name "properties". The
value of the properties member is an object (any JSON object or a
JSON null value).

As it is correctly pointed out Feature has several convenience methods to modify properties. For those methods to work we have to create an empty JsonObject whenever null is passed for properties into the factory methods.

Please note that toJson will serialize empty JsonObject (properties) as null and fromJson will create empty JsonObject whenever property is null in the json string.

Closing as not a bug.

[osana]

Actually there needs to be a fix in one line:

mapbox-java/services-geojson/src/main/java/com/mapbox/geojson/Feature.java

Line 168 in 9fa87fb

return new AutoValue_Feature(TYPE, bbox, id, geometry, properties);

it should be:
return new AutoValue_Feature(TYPE, bbox, id, geometry, properties == null ? new JsonObject() : properties);

[osana]

@tobrun Are you ok to close it , given above context

[osana]

Closing as all related work to this pr was done