presto-geospatial-toolkit/src/main/java/io/prestosql/geospatial/serde/GeometrySerde.java/GeometrySerde/readGeometryCollection
class GeometrySerde:    private static OGCConcreteGeometryCollection readGeometryCollection(BasicSliceInput input, Slice inputSlice)
    {
        // GeometryCollection: geometryType|len-of-shape1|bytes-of-shape1|len-of-shape2|bytes-of-shape2...
        List<OGCGeometry> geometries = new ArrayList<>();
        while (input.available() > 0) {
            int length = input.readInt() - 1;
            GeometrySerializationType type = GeometrySerializationType.getForCode(input.readByte());
            geometries.add(readGeometry(input, inputSlice, type, length));
        }
        return new OGCConcreteGeometryCollection(geometries, null);
    }