@Bean
    @ConditionalOnMissingBean(value = SignService.class, search = SearchStrategy.ALL)
    public SignService signService() {
        return new ComposableSignService(new DefaultExtractor(), new DefaultSignProvider());
    }
Sign service.

@return the sign service
shenyu-spring-boot-starter/shenyu-spring-boot-starter-plugin/shenyu-spring-boot-starter-plugin-sign/src/main/java/org/apache/shenyu/springboot/starter/plugin/sign/SignPluginConfiguration.java