presto-main/src/main/java/io/prestosql/connector/system/TransactionsSystemTable.java/TransactionsSystemTable/createStringsBlock
class TransactionsSystemTable:    private static Block createStringsBlock(List<CatalogName> values)
    {
        VarcharType varchar = createUnboundedVarcharType();
        BlockBuilder builder = varchar.createBlockBuilder(null, values.size());
        for (CatalogName value : values) {
            if (value == null) {
                builder.appendNull();
            }
            else {
                varchar.writeString(builder, value.getCatalogName());
            }
        }
        return builder.build();
    }