GUAC-1170: Use checked versions of empty list/set/map.

guacamole/src/main/java/org/glyptodon/guacamole/net/basic/rest/connection/APIConnectionWrapper.java

@@ -122,7 +122,7 @@ public class APIConnectionWrapper implements Connection {
 
     @Override
     public List<? extends ConnectionRecord> getHistory() throws GuacamoleException {
-        return Collections.EMPTY_LIST;
+        return Collections.<ConnectionRecord>emptyList();
     }
     
 }

guacamole/src/main/java/org/glyptodon/guacamole/net/basic/rest/language/LanguageRESTService.java

@@ -108,7 +108,7 @@ public class LanguageRESTService {
         
         // If no translation files found, return an empty map
         if (resourcePaths == null)
-            return Collections.EMPTY_MAP;
+            return Collections.<String, String>emptyMap();
         
         Map<String, String> languageMap = new HashMap<String, String>();