populate credentials field for loadTableResponse

[wolflex888]

Previously, we are not populating the Credentials field for LoadTableResponse and we are using that field to populate the result of LoadCredentials endpoint. This PR cleans up the code a bit and populate the configs and credentials.

[eric-maynard]

I think we must populate it, right? Or else how does credential vending work?

[wolflex888]

I think we must populate it, right? Or else how does credential vending work?

hmm when we were testing the endpoint, the endpoint was returning an empty array. that's why we want to put up a PR to fix it!

[eric-maynard]

@wolflex888 can you share how you did that testing?

[wolflex888]

@wolflex888 can you share how you did that testing?

@eric-maynard We are running an instance within our organization and the endpoint /credentials was not returning any data. When we are tracking it down, we found out that credentials field is not being populated. Maybe, I missed something on the way. Did you see credentials field getting populated? Currently, I don't think Iceberg is using that field either, but i can be wrong.

[eric-maynard]

I see @wolflex888, that makes sense. Can you confirm that for the same table, you see vended credentials though? Are they in the config or in credentials?

[wolflex888]

I see @wolflex888, that makes sense. Can you confirm that for the same table, you see vended credentials though? Are they in the config or in credentials?

@eric-maynard Yes, The vended credentials only lives in config right now and iceberg uses that field in loadTable to initiate tableSession and tableFileIO as well. I am populating this field so our loadCredentials will work. AFAIK they are not using the credentials field.

Also iceberg also relies on Polaris to pass back a few more additional configs so it understands this table is using vended-credentials. I put up another PR on this here