Hello, I was testing this library with some of my Garmin GPX files that include HR, cadence and temperature data in them, but I saw that only one of these data sequences is included in the output FeatureCollection. From reading the GeoJson spec, it seems the properties member cannot be an array, but it could contain a map with the key being the tag name (such as hr, cad, etc...), and the value being the data sequence, could it not? That way the data can be manipulated later, and it is tagged in some way, since currently you have no idea what the data sequence represents, it has no label. If performance or memory were a concern, perhaps an optional flag could be used to parse all extensions?