title: Spring request mapping not working when specified in interface
body: <p>I write request mapping at interface but it's not working.</p>
  
  <p>Request / response body POJOs:</p>
  
  <pre class="lang-java prettyprint-override"><code>public class ReqAa {
      private String firstValue;
      private String secondValue;
  
      public String getFirstValue() {
          return firstValue;
      }
  
      public ReqAa setFirstValue(String firstValue) {
          this.firstValue = firstValue;
          return this;
      }
  
      public String getSecondValue() {
          return secondValue;
      }
  
      public ReqAa setSecondValue(String secondValue) {
          this.secondValue = secondValue;
          return this;
      }
  }
  
  public class RespAa{
      private String status;
  
      RespAa(String status){
          this.status = status;
      }
  
      public String getStatus() {
          return status;
      }
  
      public RespAa setStatus(String status) {
          this.status = status;
          return this;
      }
  }
  </code></pre>
  
  <p>Interfaces:</p>
  
  <pre class="lang-java prettyprint-override"><code>public interface A{
      interface Aa{
          @PostMapping("/do/something")
          RespAa doSomething(@RequestBody ReqAa);
      }
  
      interface Ab{
          @PostMapping("/do/another")
          RespAb doAnother(@RequestBody ReqAb);
      }
  
  }
  
  @PreAuthorize("hasAuthority('admin')")
  @RequestMapping("/api/admin")
  public interface IClient extends A.Aa{
  }
  </code></pre>
  
  <p>Rest Controller:</p>
  
  <pre class="lang-java prettyprint-override"><code>@RestController
  public class Client implements IClient{
      @Override
      public RespAa doSomething(ReqAa reqAa) {
          return new RespAa("SUCCESS");
      }
  }
  </code></pre>
  
  <p>Spring boot <code>@RequestBody</code> could not mapping as Body. Its took it as parameter.</p>
  
  <p>Example: </p>
  
  <p>generated request: <code>/api/admin/do/something?firstValue=fv&amp;secondValue=sv</code></p>
  
  <p>expected mapping: <code>/api/admin/do/something</code></p>
  
  <p>requestBody: <code>{ "firstValue":"fv","secondValue":"sv"}</code></p>
  
  <p>its work when i used @RequestBody in implementaion method.</p>
  
  <pre><code>@RestController
  public class Client implements IClient{
      @Override
      public RespAa doSomething(@RequestBody ReqAa reqAa) {
          return new RespAa("SUCCESS");
      }
  }
  </code></pre>
  
  <p>I used spring boot version: <code>1.5.10</code>.</p>