class RpcEnvironmentApplicationListener
                                              implements
                                              ApplicationListener<ApplicationEnvironmentPreparedEvent> {

    @Override
    public void onApplicationEvent(ApplicationEnvironmentPreparedEvent event) {<FILL_FUNCTION_BODY>}
}

        Environment env = event.getEnvironment();
        String defaultTracer = env.getProperty("sofa.boot.rpc.defaultTracer");
        if (defaultTracer != null) {
            RpcConfigs.putValue(RpcOptions.DEFAULT_TRACER, defaultTracer);
        }
    
<no_super_class>