@Bean
        public PrincipalResolver defaultPrincipalResolver() throws Throwable {
            val mockPrincipalResolver = mock(PrincipalResolver.class);
            when(mockPrincipalResolver.resolve(any())).thenReturn(NullPrincipal.getInstance());
            return mockPrincipalResolver;
        }
This is {@link OAuth20ClientIdClientSecretAuthenticatorTests}.

@author Misagh Moayyed
@since 6.0.0
support/cas-server-support-oauth/src/test/java/org/apereo/cas/support/oauth/authenticator/OAuth20ClientIdClientSecretAuthenticatorTests.java