@Test
    public void testGetExtensionLoaderNotSpiAnnotation() {
        try {
            ExtensionLoader.getExtensionLoader(NopSPI.class);
            fail();
        } catch (IllegalArgumentException expected) {
            assertThat(expected.getMessage(),
                    containsString("extension clazz (interface org.apache.shenyu.spi.fixture.NopSPI) without @interface org.apache.shenyu.spi.SPI Annotation"));
        }
    }
test ExtensionLoader.getExtensionLoader() param is not have SPI annotation case.
shenyu-spi/src/test/java/org/apache/shenyu/spi/ExtensionLoaderTest.java