The FeedMetadata that is posted to the save draft endpoint contains source data sets with null titles. It doesn't look like the UI is retaining state of the newly-created data sets; created earlier during configuration of the feed transformation.
Begin to create a data transformation feed
Enter feed transformation
Select a JDBC data source and table, then add
at this point the data set will be created and the title will be set correctly. But once "save" is selected from this view a full FeedMetadata will be posted containing the source data sets, but their titles will be null. When we update the data sets in JCR based on the posted data the titles will be blanked out in the metadata.