Transpose(Normalize): No error message is displayed when comma separated field values are provided but fields are highlighted, example need to be more clear

Description

If comma separated field names are provided and validated then no error message is displayed but number of errors are displayed and only fields are highlighted.

Steps to reproduce:

1. Launch the latest CDAP (6.8.0)

2. Open Transpose plugin under transform.

3. Establish connection from GCS source to Transpose to BigQuery sink.

4. Fill the properties of Transpose by providing mandatory fields to be mapped and along with fields to be normalized, using comma separated field names and click on validate.

5. Fields are highlighted but no error is displayed.

6. Also, when close the properties page and then open plugin properties page again, then comma separated are added in new line, even if fields to normalize is provided correctly error displays.

Expected: Proper error message need to be displayed if invalid format is provided. Also, in documentation comma separated example format needs to be more clear.
Actual: As per documentation when field values/names are provided then error is displayed with no error message. Comma separated field names example is not clear.