private Optional<RsaJsonWebKey> findRsaJsonWebKeyByProvidedKeyId(final List<JsonWebKey> keys) {
        val predicate = this.keyIdToUse
            .<Predicate<JsonWebKey>>map(s -> jsonWebKey -> jsonWebKey.getKeyId()
                .equalsIgnoreCase(s))
            .orElseGet(() -> jsonWebKey -> true);
        return findRsaJsonWebKey(keys, predicate);
    }
This is {@link JsonWebKeySetStringCipherExecutor}.

@author Misagh Moayyed
@since 5.3.0
core/cas-server-core-util-api/src/main/java/org/apereo/cas/util/cipher/JsonWebKeySetStringCipherExecutor.java