Convert a row to a nested JSON document containing all relations in PostgreSQL

Hello.

In PostgreSQL 10.10, I have created a trigger function that converts the `NEW` row to a JSON object using `to_jsonb(NEW)`. But now I need to include the records on the other side of the foreign keys in `NEW` record in the JSON object in a nested fashion.

What is the best and most generic way to accomplish this without prior knowledge about the schema of the `NEW` record? I need to keep this trigger function as generic as possible, because I plan to use it on all tables. One level of depth in following foreign keys is currently enough for me.

Thank you.