title: @ApiParam type not supported to other than string
body: <pre><code>@GetMapping(value = "/result")
      public int addition(
                      @ApiParam(value = "FirstValue", required = true, type = "string", defaultValue = "0") @RequestParam(value = "firstValue", required = true) Integer x,
                      @ApiParam(value = "SecondValue", required = true, type = "string", defaultValue = "0") @RequestParam(value = "secondValue", required = true) Integer y) {
  
          return x + y;
      }
  </code></pre>
  
  <p>while refresh the swagger UI page we are getting following error</p>
  
  <pre><code>2019-06-26 15:44:11.484  WARN 16667 --- [nio-7854-exec-3] i.s.m.p.AbstractSerializableParameter    : Illegal DefaultValue 0 for parameter type integer
  
  java.lang.NumberFormatException: For input string: ""
      at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65) ~[na:1.8.0_144]
      at java.lang.Long.parseLong(Long.java:601) ~[na:1.8.0_144]
      at java.lang.Long.valueOf(Long.java:803) ~[na:1.8.0_144]
      at io.swagger.models.parameters.AbstractSerializableParameter.getExample(AbstractSerializableParameter.java:412) ~[swagger-models-1.5.20.jar:1.5.20]
      at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_144]
      at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_144]
      at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_144]
      at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_144]
  </code></pre>