@Test()
    public void testGetNonExistingUser() throws Exception
    {
        // Setup test fixture.
        HybridUserPropertyProvider.PRIMARY_PROVIDER.setValue(TestUserPropertyProvider.NoUserProvider.class);
        HybridUserPropertyProvider.SECONDARY_PROVIDER.setValue(TestUserPropertyProvider.JaneUserProvider.class);
        HybridUserPropertyProvider.TERTIARY_PROVIDER.setValue(TestUserPropertyProvider.JohnUserProvider.class);
        final HybridUserPropertyProvider provider = new HybridUserPropertyProvider();

        // Execute system under test & Verify results.
        assertThrows(UserNotFoundException.class, () -> provider.loadProperties("non-existing-user"));
    }
Verifies that an exception is thrown when properties for non-existing user are being requested.
xmppserver/src/test/java/org/jivesoftware/openfire/user/property/HybridUserPropertyProviderTest.java