presto-geospatial-toolkit/src/main/java/io/prestosql/geospatial/serde/GeometrySerde.java/GeometrySerde/getGeometryCollectionOverallEnvelope
class GeometrySerde:    private static Envelope getGeometryCollectionOverallEnvelope(BasicSliceInput input)
    {
        Envelope overallEnvelope = null;
        while (input.available() > 0) {
            int length = input.readInt() - 1;
            GeometrySerializationType type = GeometrySerializationType.getForCode(input.readByte());
            Envelope envelope = getEnvelope(input, type, length);
            overallEnvelope = merge(overallEnvelope, envelope);
        }
        return overallEnvelope;
    }