@Test
    public void testBlankDefaultUrl() {
        defaultUrl = Pac4jConstants.EMPTY_STRING;
        TestsHelper.expectException(this::call, TechnicalException.class, "defaultUrl cannot be blank");
    }
Tests {@link DefaultCallbackLogic}.

@author Jerome Leleu
@since 1.9.0
pac4j-core/src/test/java/org/pac4j/core/engine/DefaultCallbackLogicTests.java