Column pairings that make up the foreign key (an array to support composite keys).
OptionalNameConstraint name if the remote catalog supplies one.
Name of the object this relationship points to.
OptionalReferencedSchema/namespace of the referenced object, when applicable.
A foreign-key relationship discovered during schema introspection: this object's column(s) reference another object's column(s). Modeled on the referencing side (the object that holds the foreign key), mirroring how relational catalogs report constraints.