presto-sqlserver/src/main/java/io/prestosql/plugin/sqlserver/SqlServerClient.java/SqlServerClient/toPrestoType
class SqlServerClient:    @Override
    public Optional<ColumnMapping> toPrestoType(ConnectorSession session, Connection connection, JdbcTypeHandle typeHandle)
    {
        Optional<ColumnMapping> mapping = getForcedMappingToVarchar(typeHandle);
        if (mapping.isPresent()) {
            return mapping;
        }
        // TODO implement proper type mapping
        return super.toPrestoType(session, connection, typeHandle)
                .map(columnMapping -> new ColumnMapping(
                        columnMapping.getType(),
                        columnMapping.getReadFunction(),
                        columnMapping.getWriteFunction(),
                        columnMapping.getWriteNullFunction(),
                        DISABLE_UNSUPPORTED_PUSHDOWN));
    }