@NonNull abstract fun setAttribute(@NonNull @Size(1, 128) key: String, @NonNull value: String): Editor
Sets a key/value pair as an attribute in the registration. This key must already exist in your Marketing Cloud Server configuration. There is no way to add an attribute from the SDK.
key - String: a non-null string between 1 and 128 characters in length.
value - String: a non-null string
Return
Editor: RegistrationManager.Editor