Getting Metadata for Native visuals or Custom visuals installed on the report

[Anonymous]

I'm looking at the Visual Creator demo in the playground, and came across this line in the following data binding writeup: https://github.com/microsoft/powerbi-report-authoring/wiki/Data-binding#get-data-fields 

Retrieving visual metadata is available for Native visuals or Custom visuals that are installed on the report.

Does this mean that a visual on a report has access to report metadata?

Or, that the report has access to any report's visuals metadata? 

Instead of a hard coded list of data fields, I'm interested in getting the list of data fields available to the report.

Thanks for any response.