set fallback locale to English, ultimate fall through is to return the code string itself

openid-connect-server-webapp/src/main/webapp/WEB-INF/views/home.jsp

@@ -3,7 +3,7 @@
 <%@ taglib prefix="spring" uri="http://www.springframework.org/tags"%>
 <%@ taglib prefix="security" uri="http://www.springframework.org/security/tags"%>
 
-<spring:message code="home.welcome" var="title"/>
+<spring:message code="home.title" var="title"/>
 <o:header title="${title}" />
 <o:topbar pageName="Home" />
 <div class="container-fluid main">

openid-connect-server-webapp/src/main/webapp/resources/js/locale/en/messages.json

@@ -363,5 +363,13 @@
 			"number_clients": "Authorized clients: <span class=\"label label-info\" id=\"clientCount\">{0}</span>",
 			"number_approvals": "Approved sites: <span class=\"label label-info\" id=\"approvalCount\">{0}</span>"
 		}
+	},
+	"topbar": {
+		"about": "About",
+		"contact": "Contact",
+		"statistics": "Statistics",
+		"home": "Home",
+		"login": "Log in",
+		"logout": "Log out"
 	}
 }

openid-connect-server/src/main/java/org/mitre/openid/connect/config/JsonMessageSource.java

@@ -47,6 +47,8 @@ public class JsonMessageSource extends AbstractMessageSource {
 	private static final Logger logger = LoggerFactory.getLogger(JsonMessageSource.class);
 
 	private Resource baseDirectory;
+	
+	private Locale fallbackLocale = new Locale("en"); // US English is the fallback language
 
 	private Map<Locale, JsonObject> languageMaps = new HashMap<>();
 	
@@ -55,9 +57,20 @@ public class JsonMessageSource extends AbstractMessageSource {
 		
 		JsonObject lang = getLanguageMap(locale);
 
-		MessageFormat mf = getMessageFormat(code, locale, lang);
+		String value = getValue(code, lang);
+		
+		if (value == null) {
+			// if we haven't found anything, try the default locale
+			lang = getLanguageMap(fallbackLocale);
+			value = getValue(code, lang);
+		}
+		
+		if (value == null) {
+			value = code;
+		}
+
+		MessageFormat mf = new MessageFormat(value, locale);
 		
-		// TODO Auto-generated method stub
 		return mf;
 	}
 
@@ -67,14 +80,19 @@ public class JsonMessageSource extends AbstractMessageSource {
 	 * @param lang
 	 * @return
 	 */
-	private MessageFormat getMessageFormat(String code, Locale locale, JsonObject lang) {
+	private String getValue(String code, JsonObject lang) {
+		
+		// if there's no language map, nothing to look up
+		if (lang == null) {
+			return null;
+		}
 		
 		JsonElement e = lang;
 		
 		Iterable<String> parts = Splitter.on('.').split(code);
 		Iterator<String> it = parts.iterator();
 		
-		String value = code;
+		String value = null;
 		
 		while (it.hasNext()) {
 			String p = it.next();
@@ -99,9 +117,8 @@ public class JsonMessageSource extends AbstractMessageSource {
 		}
 		
 		
-		MessageFormat mf = new MessageFormat(value, locale);
+		return value;
 		
-		return mf;
 	}
 
 	/**