Context

This feature requests comes from the discussion in #2669.

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What problem are you trying to solve?

We currently have the ability to set warnings on unknown keys within an object of Joi, but not recursively. It would be nice to have the ability to say "I have an object and if I receive any unknown keys at any depth, I'd like to warn the user." The following technically works, but is not great as it can hide future problems validating joi config.

const wrappedJoiObjectWithUnknownWarnings = <TSchema = any, T = TSchema>(schema?: SchemaMap<T>): ObjectSchema<TSchema> =>
  joi.object(schema)
    .pattern(/.*/, joiInstance.any().warning(`any.unknown`))

joiInstance.object = wrappedJoiObjectWithUnknownWarnings

Do you have a new or modified API suggestion to solve the problem?

Joi.object().pattern(/.*/, Joi.any().warning('any.unknown'));

Given the single-level warning above, I'm not sure what the best approach here would be. Attaching a recursive argument into one of these would make sense, but doesn't feel right in any of the method calls. My initial idea is to add a Joi.rules or some other top-level method to set up these types of controls.