fix possible nullpointerexception

scm-webapp/src/main/java/sonia/scm/ClassOverrides.java

@@ -41,6 +41,7 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import sonia.scm.util.AssertUtil;
+import sonia.scm.util.Util;
 
 //~--- JDK imports ------------------------------------------------------------
 
@@ -49,6 +50,7 @@ import java.io.IOException;
 import java.net.URL;
 
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.Enumeration;
 import java.util.Iterator;
 import java.util.List;
@@ -218,7 +220,11 @@ public class ClassOverrides implements Iterable<ClassOverride>
    */
   public List<? extends Module> getModules()
   {
-    return Lists.transform(moduleClasses,
+    List<? extends Module> modules = null;
+
+    if (Util.isNotEmpty(moduleClasses))
+    {
+      modules = Lists.transform(moduleClasses,
                                 new Function<Class<? extends Module>, Module>()
       {
         @Override
@@ -241,6 +247,13 @@ public class ClassOverrides implements Iterable<ClassOverride>
         }
       });
     }
+    else
+    {
+      modules = Collections.EMPTY_LIST;
+    }
+
+    return modules;
+  }
 
   /**
    * Method description