private URL agentAttached() {
        String agentClass = AgentLibraryPluginFilter.BOOTSTRAP;
        return ClassLoader.getSystemClassLoader().getResource(agentClass);
    }
@author Woonduk Kang(emeroad)
@author HyunGil Jeong
@author Taejin Koo
commons-server/src/main/java/com/navercorp/pinpoint/common/server/util/ServerTraceMetadataLoaderService.java