@Test
    void verifyCustomSource() {
        val theme = themeSource.getTheme("my-theme");
        assertNotNull(theme);
        val message = theme.getMessageSource().getMessage("cas.theme.name",
            ArrayUtils.EMPTY_OBJECT_ARRAY, Locale.ENGLISH);
        assertEquals("MyTheme2", message);
        val message2 = theme.getMessageSource().getMessage("screen.welcome.instructions",
            ArrayUtils.EMPTY_OBJECT_ARRAY, Locale.ENGLISH);
        assertEquals("Test123", message2);
    }
This is {@link AggregateCasThemeSourceTests}.

@author Hal Deadman
@since 6.6.8
support/cas-server-support-themes/src/test/java/org/apereo/cas/services/web/AggregateCasThemeSourceTests.java