The Claim Names within this object MUST be unique.
Note however, that the set of claims that a JWT must contain to be considered valid is context-dependent and is outside the scope of this specification. When used in a security-related context, implementations MUST understand and support all of the claims present; otherwise, the JSON Web Token MUST be rejected for processing.
There are three classes of JWT Claim Names:
Registered Claim Names are an IANA Registry defined in JSON Web Token (RFC 7519) available in the IANA Registry JSON Web Token Claims Registry or be defined as a URI that contains a collision resistant namespace.