Possibility to request the full certificate chain programmatically

[Vampire]

Is your feature request related to a problem or specific use case? Please describe.
I try to get client-side hashing signing working, in my current use-case using JSign.
In the framework JSign is providing, before the actual signing the certificate chain is needed.
But the only way I found is to do a dummy-signing first, getting the signer certificate from the signing result.
And even then as far as I have seen, there is only the signer certificate itself, not the full certificate chain.
It would be nice if I could somehow get from the PlainSigner the full certificate chain via the "REST Interface", without triggering an actual signing process.

Describe the solution you'd like
I want to be able to get the full certificate chain programmatically that will be used for signing when I subsequently do a request to https://signserver.company.com/signserver/rest/v1/workers/PlainSigner/process.

Describe alternatives you've considered
n/a

Product deployment
Please complete the following information:

• Deployment format: container
• Version 6.3.0.Final