presto-main/src/main/java/io/prestosql/operator/aggregation/state/KeyValuePairStateSerializer.java/KeyValuePairStateSerializer/deserialize
class KeyValuePairStateSerializer:    @Override
    public void deserialize(Block block, int index, KeyValuePairsState state)
    {
        state.set(new KeyValuePairs(mapType.getObject(block, index), state.getKeyType(), state.getValueType()));
    }