Classification Schema: Adding an optional attribute that conflicts with site-level required schema should throw backend validation, at minimum

[reganwolfrom]

Currently, it's possible to create an classification schema attribute with the same key as a required site schema attribute; this should not be allowed, as the required attribute cannot be overridden.

For example, if the site-level schema has an attribute with a key of dataClassification that is a required string, when setting up a classification schema, attempting to add dataClassification as an optional attribute should fail validation, because the attribute is already listed as required as the site level.

Conversely, if dataClassification is only optional at the site level, it is valid to have dataClassification as a required attribute in a classification schema.