After a successful registration ceremony, the {@link RegistrationResult#getKeyId()} method + * returns a value suitable for inclusion in this set. + * + *
Implementations of this method MUST NOT return null.
+ *
+ * @param username
+ */
+ @Override
+ public Set Used to look up the user handle based on the username, for authentication ceremonies where
+ * the username is already given.
+ *
+ * Implementations of this method MUST NOT return null.
+ *
+ * @param username
+ */
+ @Override
+ public Optional Used to look up the username based on the user handle, for username-less authentication
+ * ceremonies.
+ *
+ * Implementations of this method MUST NOT return null.
+ *
+ * @param userHandle
+ */
+ @Override
+ public Optional The returned {@link RegisteredCredential} is not expected to be long-lived. It may be read
+ * directly from a database or assembled from other components.
+ *
+ * Implementations of this method MUST NOT return null.
+ *
+ * @param credentialId
+ * @param userHandle
+ */
+ @Override
+ public Optional This is used to refuse registration of duplicate credential IDs. Therefore, under normal
+ * circumstances this method should only return zero or one credential (this is an expected
+ * consequence, not an interface requirement).
+ *
+ * Implementations of this method MUST NOT return null.
+ *
+ * @param credentialId
+ */
+ @Override
+ public Set