output: #fixed code
                                  @SuppressWarnings("unchecked")
  	@Test
      // Add the MetadataLinkListener to the listener chain. The output will render an href to view the metadata
      // for the album object.
      public void testMetadataHref()
      {
          String prefixUrl = "/metadata/";
          String fileExtension = "test";
          Album signOfTheTimes = DataGenerator.signOfTheTimes();
  
          DefaultMetaDataRegistry service = new DefaultMetaDataRegistry();
          service.setRootMetaDataUrl( prefixUrl );
          service.setCoreSelector( new CoreSelector( populatorRegistry ) );
  
          Map<String,Class<?>> typeMappings = new HashMap<String, Class<?>>();
          typeMappings.put( "album", Album.class );
          service.setTypeMappings( typeMappings );
  
          MetadataLinkListener metadataLinkListener = new MetadataLinkListener();
          metadataLinkListener.setMetaDataRegistry( service );
  
          ResultTraverser traverser = new ResultTraverser();
          YogaRequestContext requestContext = new YogaRequestContext( fileExtension, new GDataSelectorParser(),
                  new DummyHttpServletRequest(), new DummyHttpServletResponse(), metadataLinkListener );
          Map<String, Object> objectTree = doTraverse( signOfTheTimes, "", traverser, requestContext );
  
          Map<String,String> metadataMap = (Map<String,String>) objectTree.get( "metadata" );
          String metadataHref = prefixUrl + "album." + fileExtension;
          Assert.assertEquals( metadataHref, metadataMap.get( "href" ) );
      }
input: #vulnerable code 
                                  @SuppressWarnings("unchecked")
  	@Test
      // Add the MetadataLinkListener to the listener chain. The output will render an href to view the metadata
      // for the album object.
      public void testMetadataHref()
      {
          String prefixUrl = "/metadata/";
          String fileExtension = "test";
          Album signOfTheTimes = DataGenerator.signOfTheTimes();
  
          DefaultMetaDataRegistry service = new DefaultMetaDataRegistry();
          service.setRootMetaDataUrl( prefixUrl );
          service.setCoreSelector( new CoreSelector( populatorRegistry ) );
  
          Map<String,Class<?>> typeMappings = new HashMap<String, Class<?>>();
          typeMappings.put( "album", Album.class );
          service.setTypeMappings( typeMappings );
  
          MetadataLinkListener metadataLinkListener = new MetadataLinkListener();
          metadataLinkListener.setMetaDataRegistry( service );
  
          ResultTraverser traverser = new ResultTraverser();
          YogaRequestContext requestContext = new YogaRequestContext( fileExtension,
                  new DummyHttpServletRequest(), new DummyHttpServletResponse(), metadataLinkListener );
          Map<String, Object> objectTree = doTraverse( signOfTheTimes, ":", traverser, requestContext );
  
          Map<String,String> metadataMap = (Map<String,String>) objectTree.get( "metadata" );
          String metadataHref = prefixUrl + "album." + fileExtension;
          Assert.assertEquals( metadataHref, metadataMap.get( "href" ) );
      } 
                              #location 27 
                              #vulnerability type NULL_DEREFERENCE