toWKT method
Converts the FeatureCollection to a WKT string.
Example:
FeatureCollection([
Point(Coordinate(1, 2)),
Point(Coordinate(3, 4))
]).toWKT(); // GEOMETRYCOLLECTION(POINT(1 2), POINT(3 4))
Implementation
String toWKT() {
return 'GEOMETRYCOLLECTION(${features.map((f) => f.toWKT()).join(',')})';
}