private Object getAttachment(InterceptorScopeInvocation invocation) {
        if (invocation == null) {
            return null;
        }
        return invocation.getAttachment();
    }
@author Minwoo Jung
@author jaehong.kim
agent-module/plugins/httpclient3/src/main/java/com/navercorp/pinpoint/plugin/httpclient3/interceptor/HttpMethodBaseExecuteMethodInterceptor.java