presto-main/src/main/java/io/prestosql/operator/aggregation/state/BlockPositionStateSerializer.java/BlockPositionStateSerializer/deserialize
class BlockPositionStateSerializer:    @Override
    public void deserialize(Block block, int index, BlockPositionState state)
    {
        // Use the original serialized block as the underlying block for the state to save object creation overhead
        state.setPosition(index);
        state.setBlock(block);
    }