Fix #35505: send lang as header

Author: LEDfan

src/main/java/eu/openanalytics/containerproxy/model/runtime/runtimevalues/HttpHeaders.java

@@ -24,6 +24,7 @@
 import com.fasterxml.jackson.annotation.JsonValue;
 import eu.openanalytics.containerproxy.auth.impl.OpenIDAuthenticationBackend;
 import eu.openanalytics.containerproxy.model.runtime.Proxy;
+import eu.openanalytics.containerproxy.service.LanguageService;
 import io.undertow.util.HeaderMap;
 import io.undertow.util.HttpString;
 import org.slf4j.Logger;
@@ -56,6 +57,7 @@ public HttpHeaders(Map<String, String> headers) {
 
     public HeaderMap getUndertowHeaderMap(Proxy proxy) {
         undertowHeaderMap.putAll(OpenIDAuthenticationBackend.addHeaders(proxy));
+        undertowHeaderMap.putAll(LanguageService.addHeaders());
         return undertowHeaderMap;
     }
 

src/main/java/eu/openanalytics/containerproxy/service/LanguageService.java

@@ -21,6 +21,8 @@
 package eu.openanalytics.containerproxy.service;
 
 import eu.openanalytics.containerproxy.util.EnvironmentUtils;
+import io.undertow.util.HeaderMap;
+import io.undertow.util.HttpString;
 import jakarta.servlet.http.HttpServletRequest;
 import jakarta.servlet.http.HttpServletResponse;
 import org.apache.commons.lang3.StringUtils;
@@ -42,6 +44,7 @@
 public class LanguageService {
 
     private static final String PROP_PROXY_AVAILABLE_LANGUAGES = "proxy.available-languages";
+    private static final HttpString HEADER_LANGUAGE_NAME = new HttpString("X-SP-Language");
     private static final Map<String, Language> DEFAULT_AVAILABLE_LANGUAGES = Map.of(
         "en", new Language("en", "English"),
         "nl", new Language("nl", "Dutch"),
@@ -112,4 +115,11 @@ public record Language(String key, String displayName) {
 
     }
 
+    public static HeaderMap addHeaders() {
+        HeaderMap result = new HeaderMap();
+        String language = LocaleContextHolder.getLocale().getLanguage();
+        result.add(HEADER_LANGUAGE_NAME, language);
+        return result;
+    }
+
 }