title: Swagger UI not working when Spring controller uses parameter Map
body: <p>We are using Swagger and Spring Fox version 2.5.0, POM entry below.  When we create a Spring MVC controller that has uses a parameter Map (see example below), then the Swagger-UI page does not properly generate.  The controller in question does not appear on the Swagger-UI page and none of the controllers that come after it appear also (in alphabetical order).</p>
  
  <pre><code>@RequestMapping(value = "/resource/", method = RequestMethod.GET, produces = {"application/json"})
  public void get(@RequestParam MultiValueMap&lt;String, String&gt; params) {
       //code
  }
  </code></pre>
  
  <p>When the params Map is removed, then everything is fine.  Any idea what the issue could be or how to get around it? </p>
  
  <p>Below is more info that may or may not be useful.</p>
  
  <p>the dependencies: </p>
  
  <pre><code>    &lt;dependency&gt;
          &lt;groupId&gt;io.springfox&lt;/groupId&gt;
          &lt;artifactId&gt;springfox-swagger2&lt;/artifactId&gt;
          &lt;version&gt;2.5.0&lt;/version&gt;
      &lt;/dependency&gt;
      &lt;dependency&gt;
          &lt;groupId&gt;io.springfox&lt;/groupId&gt;
          &lt;artifactId&gt;springfox-swagger-ui&lt;/artifactId&gt;
          &lt;version&gt;2.5.0&lt;/version&gt;
      &lt;/dependency&gt;
  </code></pre>
  
  <p>the Swagger config:</p>
  
  <pre><code>@Configuration
  @EnableSwagger2
  public class SwaggerConfiguration {
  
      @Bean
      public Docket api() {
          Docket docket = new Docket(DocumentationType.SWAGGER_2)
                  .apiInfo(apiInfo())
                  .select()
                  .paths(PathSelectors.any())
                  .build();
          docket.ignoredParameterTypes(Principal.class);
          return docket;
      }
  
      private ApiInfo apiInfo() {
          return new ApiInfoBuilder().title("some app")
                  .description("some description")
                  .build();
      }
  }
  </code></pre>