--- old/src/jdk.jlink/share/classes/jdk/tools/jlink/TaskHelper.java	2015-10-03 00:56:09.236074867 +0300
+++ new/src/jdk.jlink/share/classes/jdk/tools/jlink/TaskHelper.java	2015-10-03 00:56:09.124074862 +0300
@@ -30,7 +30,10 @@
 import java.io.IOException;
 import java.io.PrintWriter;
 import java.lang.module.Configuration;
+import java.lang.module.ModuleDescriptor;
 import java.lang.module.ModuleFinder;
+import java.lang.module.ModuleReference;
+import java.lang.module.ResolutionException;
 import java.lang.reflect.Layer;
 import java.nio.file.Path;
 import java.nio.file.Paths;
@@ -44,6 +47,7 @@
 import java.util.MissingResourceException;
 import java.util.Properties;
 import java.util.ResourceBundle;
+import java.util.Set;
 
 import jdk.internal.module.ConfigurableModuleFinder;
 import jdk.internal.module.ConfigurableModuleFinder.Phase;
@@ -285,9 +289,7 @@
                         = new FileInputStream(pluginsProperties);) {
                     props.load(stream);
                 } catch (FileNotFoundException ex) {
-                    throw new IOException(bundleHelper.
-                            getMessage("err.path.not.valid")
-                            + " " + pluginsProperties);
+                    throw new IOException(bundleHelper.getMessage("err.path.not.valid", pluginsProperties));
                 }
             }
             for (Entry<PluginProvider, Map<String, String>> entry : plugins.entrySet()) {
@@ -588,6 +590,8 @@
                         : ImagePluginProviderRepository.getImageBuilderProviders(getPluginsLayer())) {
                     log.println("\n" + bundleHelper.getMessage("main.image.builder.name")
                             + ": " + prov.getName());
+                    log.println(bundleHelper.getMessage("main.image.builder.description")
+                            + ": " + prov.getDescription());
                     logBuilderOptions(prov.getOptions());
                 }
             }
@@ -675,9 +679,8 @@
                         = new FileInputStream(pluginOptions.pluginsProperties)) {
                     props.load(fis);
                 } catch (FileNotFoundException ex) {
-                    throw new IOException(bundleHelper.
-                            getMessage("err.path.not.valid")
-                            + " " + pluginOptions.pluginsProperties);
+                    throw new IOException(bundleHelper.getMessage("err.path.not.valid",
+                            pluginOptions.pluginsProperties));
                 }
                 StringBuilder sb = new StringBuilder();
                 for (String str : props.stringPropertyNames()) {
@@ -789,6 +792,21 @@
         return arguments;
     }
 
+    private static void checkExportedPackages(Set<ModuleReference> modules) {
+        Map<String, ModuleReference> packageToModule = new HashMap<>();
+        for (ModuleReference module : modules) {
+            for (String pack: module.descriptor().packages()) {
+                ModuleReference other = packageToModule.putIfAbsent(pack, module);
+                if (other != null) {
+                    String module1 = module.descriptor().name();
+                    String module2 = other.descriptor().name();
+                    throw new ResolutionException("Modules "
+                            + module1 + " and " + module2 + " both contain package " + pack);
+                }
+            }
+        }
+    }
+
     static Layer createPluginsLayer(Path[] paths) {
         ModuleFinder finder = ModuleFinder.of(paths);
 
@@ -799,6 +817,7 @@
         Configuration cf
             = Configuration.resolve(ModuleFinder.empty(), Layer.boot(), finder);
         cf = cf.bind();
+        checkExportedPackages(cf.modules());
         // The creation of this classloader is done outside privileged block in purpose
         // If a security manager is set, then permission must be granted to jlink
         // codebase to create a classloader. This is the expected behavior.