--- old/src/share/classes/com/sun/jndi/toolkit/ctx/Continuation.java	Mon May 13 06:49:15 2013
+++ new/src/share/classes/com/sun/jndi/toolkit/ctx/Continuation.java	Mon May 13 06:49:13 2013
@@ -90,14 +90,15 @@
      * Constructs a new instance of Continuation.
      * @param top The name of the object that is to be resolved/operated upon.
      *          This becomes the Continuation's 'starter' and is used to
-     *          calculate the "resolved name" when filling  in a NamingException.
+     *          calculate the "resolved name" when filling in a NamingException.
      * @param environment The environment used by the caller. It is used
-     * when setting the "environment" of a CannotProceedException.
+     *          when setting the "environment" of a CannotProceedException.
      */
     public Continuation(Name top, Hashtable<?,?> environment) {
         super();
         starter = top;
-        this.environment = environment;
+        this.environment = (Hashtable<?,?>)
+                ((environment == null) ? null : environment.clone());
     }
 
     /**
--- old/src/share/classes/com/sun/jndi/toolkit/dir/LazySearchEnumerationImpl.java	Mon May 13 06:49:18 2013
+++ new/src/share/classes/com/sun/jndi/toolkit/dir/LazySearchEnumerationImpl.java	Mon May 13 06:49:16 2013
@@ -69,6 +69,7 @@
             }
     }
 
+    @SuppressWarnings("unchecked")      // For Hashtable clone: env.clone()
     public LazySearchEnumerationImpl(NamingEnumeration<Binding> candidates,
         AttrFilter filter, SearchControls cons,
         Context ctx, Hashtable<String, Object> env, boolean useFactory)
@@ -76,7 +77,8 @@
 
             this.candidates = candidates;
             this.filter = filter;
-            this.env = env;
+            this.env = (Hashtable<String, Object>)
+                    ((env == null) ? null : env.clone());
             this.context = ctx;
             this.useFactory = useFactory;
 
--- old/src/share/classes/com/sun/jndi/toolkit/url/GenericURLContext.java	Mon May 13 06:49:21 2013
+++ new/src/share/classes/com/sun/jndi/toolkit/url/GenericURLContext.java	Mon May 13 06:49:19 2013
@@ -53,7 +53,8 @@
     @SuppressWarnings("unchecked") // Expect Hashtable<String, Object>
     public GenericURLContext(Hashtable<?,?> env) {
         // context that is not tied to any specific URL
-        myEnv = (Hashtable<String, Object>)env;  // copied on write
+        myEnv =
+            (Hashtable<String, Object>)(env == null ? null : env.clone());
     }
 
     public void close() throws NamingException {
@@ -494,7 +495,6 @@
             if (myEnv == null) {
                 return null;
             }
-            myEnv = (Hashtable<String, Object>)myEnv.clone();
             return myEnv.remove(propName);
     }
 
@@ -501,9 +501,9 @@
     @SuppressWarnings("unchecked") // clone()
     public Object addToEnvironment(String propName, Object propVal)
         throws NamingException {
-            myEnv = (myEnv == null)
-                    ? new Hashtable<String, Object>(11, 0.75f)
-                    : (Hashtable<String, Object>)myEnv.clone();
+            if (myEnv == null) {
+                myEnv = new Hashtable<String, Object>(11, 0.75f);
+            }
             return myEnv.put(propName, propVal);
     }