presto-geospatial/src/main/java/io/prestosql/plugin/geospatial/GeoFunctions.java/GeoFunctions/stStartPoint
class GeoFunctions:    @SqlNullable
    @Description("Returns the first point of a LINESTRING geometry as a Point")
    @ScalarFunction("ST_StartPoint")
    @SqlType(GEOMETRY_TYPE_NAME)
    public static Slice stStartPoint(@SqlType(GEOMETRY_TYPE_NAME) Slice input)
    {
        OGCGeometry geometry = deserialize(input);
        validateType("ST_StartPoint", geometry, EnumSet.of(LINE_STRING));
        if (geometry.isEmpty()) {
            return null;
        }
        MultiPath lines = (MultiPath) geometry.getEsriGeometry();
        SpatialReference reference = geometry.getEsriSpatialReference();
        return serialize(createFromEsriGeometry(lines.getPoint(0), reference));
    }