@Test
        void verifyServiceIssuer() {
            val registeredService = getOidcRegisteredService();
            var issuer = oidcIssuerService.determineIssuer(Optional.of(registeredService));
            assertEquals(issuer, casProperties.getAuthn().getOidc().getCore().getIssuer());
            registeredService.setIdTokenIssuer("https://custom.issuer/");
            issuer = oidcIssuerService.determineIssuer(Optional.of(registeredService));
            assertEquals("https://custom.issuer", issuer);
        }
This is {@link OidcDefaultIssuerServiceTests}.

@author Misagh Moayyed
@since 6.4.0
support/cas-server-support-oidc/src/test/java/org/apereo/cas/oidc/issuer/OidcDefaultIssuerServiceTests.java