Override JSON Content-Type sent by client for /v2

Fixes regression introduced by commit
7eec95ae.

src/main/java/de/thm/arsnova/config/AppConfig.java

@@ -100,8 +100,10 @@ import java.util.List;
 		encoding = "UTF-8"
 )
 public class AppConfig implements WebMvcConfigurer {
-	public static final MediaType API_V2_MEDIA_TYPE = new MediaType("application", "vnd.de.thm.arsnova.v2+json");
-	public static final MediaType API_V3_MEDIA_TYPE = new MediaType("application", "vnd.de.thm.arsnova.v3+json");
+	public static final String API_V2_MEDIA_TYPE_VALUE = "application/vnd.de.thm.arsnova.v2+json";
+	public static final String API_V3_MEDIA_TYPE_VALUE = "application/vnd.de.thm.arsnova.v3+json";
+	public static final MediaType API_V2_MEDIA_TYPE = MediaType.valueOf(API_V2_MEDIA_TYPE_VALUE);
+	public static final MediaType API_V3_MEDIA_TYPE = MediaType.valueOf(API_V3_MEDIA_TYPE_VALUE);
 
 	@Autowired
 	private Environment env;

src/main/java/de/thm/arsnova/controller/v2/LegacyController.java

@@ -159,7 +159,7 @@ public class LegacyController extends AbstractController {
 	}
 
 	@DeprecatedApi
-	@RequestMapping(value = "/whoami")
+	@RequestMapping(value = { "/whoami", "/whoami.json" })
 	public String redirectWhoami() {
 		return "forward:/v2/auth/whoami";
 	}

src/main/java/de/thm/arsnova/web/V2ContentTypeOverrideFilter.java

+package de.thm.arsnova.web;
+
+import de.thm.arsnova.config.AppConfig;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.MediaType;
+import org.springframework.stereotype.Component;
+import org.springframework.web.filter.OncePerRequestFilter;
+
+import javax.servlet.FilterChain;
+import javax.servlet.ServletException;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletRequestWrapper;
+import javax.servlet.http.HttpServletResponse;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Enumeration;
+import java.util.List;
+
+/**
+ * This {@link javax.servlet.Filter} overrides the Content-Type for JSON data sent by the client with the ARSnova API v2
+ * JSON Content-Type.
+ *
+ * @author Daniel Gerhardt
+ */
+@Component
+public class V2ContentTypeOverrideFilter extends OncePerRequestFilter {
+	private static final Logger logger = LoggerFactory.getLogger(V2ContentTypeOverrideFilter.class);
+	private final List<String> contentTypeHeaders;
+
+	{
+		contentTypeHeaders = new ArrayList<>();
+		contentTypeHeaders.add(AppConfig.API_V2_MEDIA_TYPE_VALUE);
+	}
+
+	@Override
+	protected void doFilterInternal(final HttpServletRequest request, final HttpServletResponse response,
+			final FilterChain filterChain) throws IOException, ServletException {
+		HttpServletRequest requestWrapper = new HttpServletRequestWrapper(request) {
+			@Override
+			public String getHeader(final String name) {
+				String header = super.getHeader(name);
+				if (header != null && HttpHeaders.CONTENT_TYPE.equals(name)
+						&& MediaType.APPLICATION_JSON.includes(MediaType.valueOf(header))) {
+					logger.debug("Overriding {} header: {}", HttpHeaders.CONTENT_TYPE, AppConfig.API_V2_MEDIA_TYPE_VALUE);
+					return AppConfig.API_V2_MEDIA_TYPE_VALUE;
+				}
+
+				return header;
+			}
+
+			@Override
+			public String getContentType() {
+				return getHeader(HttpHeaders.CONTENT_TYPE);
+			}
+
+			@Override
+			public Enumeration<String> getHeaders(final String name) {
+				String firstHeader = super.getHeaders(name).nextElement();
+				if (firstHeader != null && HttpHeaders.CONTENT_TYPE.equals(name)
+						&& MediaType.APPLICATION_JSON.includes(MediaType.valueOf(firstHeader))) {
+					logger.debug("Overriding {} header: {}", HttpHeaders.CONTENT_TYPE, AppConfig.API_V2_MEDIA_TYPE_VALUE);
+					return Collections.enumeration(contentTypeHeaders);
+				}
+
+				return super.getHeaders(name);
+			}
+		};
+		filterChain.doFilter(requestWrapper, response);
+	}
+}

src/main/webapp/WEB-INF/web.xml

@@ -86,6 +86,16 @@
 		<url-pattern>/*</url-pattern>
 	</filter-mapping>
 
+	<filter>
+		<filter-name>v2ContentTypeOverrideFilter</filter-name>
+		<filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>
+		<async-supported>true</async-supported>
+	</filter>
+	<filter-mapping>
+		<filter-name>v2ContentTypeOverrideFilter</filter-name>
+		<url-pattern>/v2/*</url-pattern>
+	</filter-mapping>
+
 	<session-config>
 		<tracking-mode>COOKIE</tracking-mode>
 	</session-config>