[CX] Query returns no result if empty string is used in USING clause while creating external dataset

While creating an external dataset on AWS s3 bucket, if an empty string is passed in USING clause, then while querying that dataset, no results are returned.

Steps to reproduce -

1. Create a link to AWS S3 bucket.
2. Create an external dataset.

CREATE EXTERNAL DATASET <dataset_name> ON <S3 bucket name> AT <external link> USING “” WITH { “format”: <format> };

3. Run a query on dataset.

SELECT * FROM <dataset_name>;