XWIKI-15140: Allow giving a chain of translations keys fallbacks to the localization script service

xwiki-platform-core/xwiki-platform-localization/xwiki-platform-localization-script/src/main/java/org/xwiki/localization/script/LocalizationScriptService.java

@@ -364,10 +364,12 @@ public String render(Collection<String> keys, Syntax syntax, Collection<?> param
         Translation translation = null;
 
         for (String key : keys) {
-            translation = this.localization.getTranslation(key, locale);
+            if (key != null) {
+                translation = this.localization.getTranslation(key, locale);
 
-            if (translation != null) {
-                break;
+                if (translation != null) {
+                    break;
+                }
             }
         }
 

xwiki-platform-core/xwiki-platform-localization/xwiki-platform-localization-script/src/test/java/org/xwiki/localization/script/LocalizationScriptServiceTest.java

@@ -113,7 +113,7 @@ public void render() throws Exception
     {
         assertEquals("print result", localizationScriptService.render("key"));
         assertEquals("print result",
-            localizationScriptService.render(Arrays.asList("not existing key", "key", "another key")));
+            localizationScriptService.render(Arrays.asList(null, "not existing key", "key", "another key")));
     }
 
     @Test
@@ -121,7 +121,7 @@ public void renderWithSyntax() throws Exception
     {
         assertEquals("print result", localizationScriptService.render("key", Syntax.PLAIN_1_0));
         assertEquals("print result", localizationScriptService
-            .render(Arrays.asList("not existing key", "key", "another key"), Syntax.PLAIN_1_0));
+            .render(Arrays.asList(null, "not existing key", "key", "another key"), Syntax.PLAIN_1_0));
     }
 
     @Test
@@ -129,15 +129,15 @@ public void renderWithSyntaxAndParameters() throws Exception
     {
         assertEquals("print result", localizationScriptService.render("key", Syntax.PLAIN_1_0, Arrays.asList()));
         assertEquals("print result", localizationScriptService
-            .render(Arrays.asList("not existing key", "key", "another key"), Syntax.PLAIN_1_0, Arrays.asList()));
+            .render(Arrays.asList(null, "not existing key", "key", "another key"), Syntax.PLAIN_1_0, Arrays.asList()));
     }
 
     @Test
     public void renderWithParameters() throws Exception
     {
         assertEquals("print result", localizationScriptService.render("key", Arrays.asList()));
-        assertEquals("print result",
-            localizationScriptService.render(Arrays.asList("not existing key", "key", "another key"), Arrays.asList()));
+        assertEquals("print result", localizationScriptService
+            .render(Arrays.asList(null, "not existing key", "key", "another key"), Arrays.asList()));
     }
 
     @Test