I worked with customer who was trying come up with a best practice for promoting task to different environments (DEV, TEST, PROD). Each environment has its own source and target definitions. When you migrate and swap the source endpoint, you lose the table definition list which is problematic to customer.
The workarounds we came up with for migrating PROD task to DEV were:
1: Imported Prod task to DEV, changed the endpoints within UI to DEV, exported task as json, updated json with table list from the original prod json file, and reimported
2: Copied a version of PROD task json, edited json to point to DEV objects definitions
Both options are fairly manual and open it up to human error.
Proposing a feature request to retain table list information in a task if you need to swap source endpoint definition.