title: Spring boot Required request parameter 'paramName' for method parameter type String is not present
body: <p>I am writing a spring boot application. But I have exception as below</p>
  <blockquote>
  <p>&quot;Internal Server Exception has been occured! Exception details: Required request parameter 'caseNumbers' for method parameter type String is not present&quot;</p>
  </blockquote>
  <p>Below is my code</p>
  <p><strong>My Controller</strong></p>
  <pre><code>public interface ReadCaseByCaseNumberController {
  
      @GetMapping(&quot;/case&quot;)
      ResponseEntity&lt;String&gt; getReadCaseByCaseNumberResponse(@RequestParam String caseNumbers) throws IOException;
  }
  </code></pre>
  <p><strong>My ControllerImpl</strong></p>
  <pre><code>@RestController
  @RequiredArgsConstructor
  public class ReadCaseByCaseNumberControllerImpl implements ReadCaseByCaseNumberController {
  
      private final ReadCaseByCaseNumberService readCaseByCaseNumberService;
  
      @Override
      public ResponseEntity&lt;String&gt; getReadCaseByCaseNumberResponse(String caseNumbers) throws IOException {
  
          return ResponseEntity.ok(readCaseByCaseNumberService.getReadCaseByCaseNumberResponse(caseNumbers));
      }
  </code></pre>
  <p><strong>My Service</strong></p>
  <pre><code>public interface ReadCaseByCaseNumberService {
  
       ReadCaseByCaseNumberResponse getReadCaseByCaseNumberResponse(String caseNumbers) throws IOException;
  }
  </code></pre>
  <p><strong>My ServiceImpl</strong></p>
  <pre><code>RestController
  @RequiredArgsConstructor
  public class ReadCaseByCaseNumberControllerImpl implements ReadCaseByCaseNumberController {
  
  @Value(&quot;${servce.urlBasePath}&quot;)
  private String urlBasePath;
  
  @Value(&quot;${service.getCaseByCaseNumberPath}&quot;)
  private String getMessageByCaseNumberURL;
  
  @Override
  public String getReadCaseByCaseNumberResponse(String caseNumbers)
  
          HttpHeaders httpHeaders = new HttpHeaders();
  
          httpHeaders.set(&quot;key&quot;, &quot;value&quot;);
          httpHeaders.set(&quot;token&quot;, &quot;token&quot;);
     
  
          HttpEntity&lt;String&gt; requestEntity = new HttpEntity&lt;&gt;(httpHeaders);
  
  
          UriComponentsBuilder builder = UriComponentsBuilder.fromHttpUrl(urlBasePath.concat(getMessageByCaseNumberURL))
                  .queryParam(&quot;caseNumbers&quot;, caseNumbers);
          
          ResponseEntity&lt;String&gt; readCaseByCaseNumberResponseResponse =
                  restTemplate.exchange(builder.build().toUriString(), HttpMethod.GET, requestEntity, String.class);
  
          if (readCaseByCaseNumberResponseResponse.getStatusCode().equals(HttpStatus.OK)) {
  
              return readCaseByCaseNumberResponseResponse.getBody();
  
          } else {
              return null;
          }
      }
  }
  </code></pre>