presto-spi/src/main/java/io/prestosql/spi/type/CharType.java/CharType/getObjectValue
class CharType:    @Override
    public Object getObjectValue(ConnectorSession session, Block block, int position)
    {
        if (block.isNull(position)) {
            return null;
        }

        Slice slice = block.getSlice(position, 0, block.getSliceLength(position));
        return padSpaces(slice, length).toStringUtf8();
    }