title: No operations defined in spec! - I get this error even though the swagger is setup and the end points are defined
body: <p>I am trying to setup swagger on top of my node application using the swagger npm package. I have my end points and swagger setup perfect(atleast almost perfect), I did do quiet a lot of research on whats going wrong but I couldn't find the trace. 
  My swagger setup file: </p>
  
  <pre><code>const express = require('express');
  const path = require('path');
  const cookieParser = require('cookie-parser');
  const bodyParser = require('body-parser');
  const swaggerJSDoc = require('swagger-jsdoc');
  const swaggerUi = require('swagger-ui-express');
  const abc= require('./routes/abc');
  var app = express();
  
  const swaggerDefinition = {
      info: {
          title: 'Analytics Project',
          version: '1.0.0',
          description: 'Analytics API swagger documentation'
      }
  };
  const options = {
      swaggerDefinition,
      apis: ['./routes/abc.js']
  };
  
  const swaggerSpec = swaggerJSDoc(options);
  
  var api = require('./routes/abc');
  app.use('/', api);
  app.use(bodyParser.json());
  app.use(bodyParser.urlencoded({ extended: false }));
  app.use(cookieParser());
  app.use('/api/v1/abc', abc);
  app.use('/api/v1/abc/scatter', abc);
  app.use('/api-docs', swaggerUi.serve, swaggerUi.setup(swaggerSpec));
  module.exports = app;
  </code></pre>
  
  <p>My end points are defined in ./routes/abc.js:</p>
  
  <pre><code>var express = require('express');
  var router = require('express').Router();
  const request = require('request');
  
  /**
   * @swagger
   * /:
   *   get:
   *     description:  Endpoint for everything
   */
  router.get('/', function(req, res, next) { //End point1
      res.send('hello from dataservice');
    });
  
  /**
   * @swagger
   * /scatter:
   *   post:
   *    description:  Endpoint for all variations of scatter plots
   */
  router.post('/scatter', function(req, res, next) { //end point2
      res.json({users: [{name: 'Timmy'}]});
    });
  module.exports = router;
  </code></pre>
  
  <p>I was expecting the 2 end points to show up on the page. But instead I get the 'No operations defined in spec!' error. What am I missing? Any help is appreciated.</p>