> What’s the history of this project? It seems to have come from nowhere to awesome in a few weeks [...]

Here's a little bit of that history.

## Alternatives { #alternatives }

I have been creating APIs with complex requirements for several years (Machine Learning, distributed systems, asynchronous jobs, NoSQL databases, etc), leading several teams of developers.

As part of that, I needed to investigate, test and use many alternatives.

        void shouldHandleResponseMapOperations() {
            assertEquals(0, transport.getResponseMapSize());
            // Response map is accessible through protected field for testing
            // but we avoid complex interactions here for performance
        }
    }

    // TLD with only 1 (wildcard) rule.
    checkPublicSuffix("mm", null)
    checkPublicSuffix("c.mm", null)
    checkPublicSuffix("b.c.mm", "b.c.mm")
    checkPublicSuffix("a.b.c.mm", "b.c.mm")
    // More complex TLD.
    checkPublicSuffix("jp", null)
    checkPublicSuffix("test.jp", "test.jp")
    checkPublicSuffix("www.test.jp", "test.jp")
    checkPublicSuffix("ac.jp", null)
    checkPublicSuffix("test.ac.jp", "test.ac.jp")

        assertTrue("Component integration test should be fast", true);
    }

    @Test
    public void test_basic_functionality() {
        // Basic functionality test without complex operations
        try {
            List<String> emptyIds = new ArrayList<>();
            dataIndexHelper.crawl("basic-test", emptyIds);
            assertTrue("Basic functionality should be fast", true);

            // Verify overwrite
            assertEquals(concreteImplementation, cacheMap.get(key));
            assertNotEquals(oldEntry, cacheMap.get(key));
        }
    }

    @Nested
    @DisplayName("Complex Scenarios Tests")
    class ComplexScenariosTests {

        @Test
        @DisplayName("Should handle multiple fixup operations")
        void testMultipleFixupOperations() {

        assertEquals(type, exception.getType());
        assertEquals(message, exception.getMessage());
    }

    @Test
    public void test_exceptionInComplexScenario() {
        // Test exception in a more complex scenario
        InvalidAccessTokenException exception = null;
        String expectedType = "Bearer";
        String expectedMessage = "Token has expired";

        // Simulate a token validation scenario

        assertNotSame(loginException.getMessageCode(), logoutException.getMessageCode());
    }

    @Test
    public void test_complexMessageCode() {
        // Setup - test with a complex message code that has parameters
        final String errorDetail = "Authentication failed";
        final VaMessenger<FessMessages> complexMessageCode =

    }

    @Test
    public void test_constructorWithThrowableCause_ChainedErrorsAndExceptions() {
        // Test with chain containing both Errors and Exceptions
        String message = "SSO login complex error chain";
        IllegalStateException innerException = new IllegalStateException("Bad state");
        AssertionError middleError = new AssertionError("Assertion failed", innerException);

    public void test_query_complexFessSyntax() {
        final String query = "title:\"security policy\"^2 OR (+security +policy (guide OR document))";
        final IntentDetectionResult result = IntentDetectionResult.search(query, "complex query");

        assertEquals(query, result.getQuery());
    }

    @Test
    public void test_faq_complexFessSyntax() {
        final String query = "+\"OpenSearch\" (configuration OR settings OR config)";

They tend to require more complex configurations, a message/job queue manager, like RabbitMQ or Redis, but they allow you to run background tasks in multiple processes, and especially, in multiple servers.