--- old/src/java.base/share/classes/java/util/Set.java	2017-09-20 16:53:10.000000000 -0700
+++ new/src/java.base/share/classes/java/util/Set.java	2017-09-20 16:53:10.000000000 -0700
@@ -63,15 +63,16 @@
  * Such exceptions are marked as "optional" in the specification for this
  * interface.
  *
- * <h2><a id="immutable">Immutable Set Static Factory Methods</a></h2>
- * <p>The {@link Set#of(Object...) Set.of()} static factory methods
- * provide a convenient way to create immutable sets. The {@code Set}
+ * <h2><a id="unmodifiable">Unmodifiable Sets</a></h2>
+ * <p>The {@link Set#of(Object...) Set.of} and
+ * {@link Set#copyOf Set.copyOf} static factory methods
+ * provide a convenient way to create unmodifiable sets. The {@code Set}
  * instances created by these methods have the following characteristics:
  *
  * <ul>
- * <li>They are <em>structurally immutable</em>. Elements cannot be added or
- * removed. Calling any mutator method will always cause
- * {@code UnsupportedOperationException} to be thrown.
+ * <li>They are <a href="Collection.html#unmodifiable"><i>unmodifiable</i></a>. Elements cannot
+ * be added or removed. Calling any mutator method on the Set
+ * will always cause {@code UnsupportedOperationException} to be thrown.
  * However, if the contained elements are themselves mutable, this may cause the
  * Set to behave inconsistently or its contents to appear to change.
  * <li>They disallow {@code null} elements. Attempts to create them with
@@ -439,8 +440,8 @@
     }
 
     /**
-     * Returns an immutable set containing zero elements.
-     * See <a href="#immutable">Immutable Set Static Factory Methods</a> for details.
+     * Returns an unmodifiable set containing zero elements.
+     * See <a href="#unmodifiable">Unmodifiable Sets</a> for details.
      *
      * @param <E> the {@code Set}'s element type
      * @return an empty {@code Set}
@@ -452,8 +453,8 @@
     }
 
     /**
-     * Returns an immutable set containing one element.
-     * See <a href="#immutable">Immutable Set Static Factory Methods</a> for details.
+     * Returns an unmodifiable set containing one element.
+     * See <a href="#unmodifiable">Unmodifiable Sets</a> for details.
      *
      * @param <E> the {@code Set}'s element type
      * @param e1 the single element
@@ -467,8 +468,8 @@
     }
 
     /**
-     * Returns an immutable set containing two elements.
-     * See <a href="#immutable">Immutable Set Static Factory Methods</a> for details.
+     * Returns an unmodifiable set containing two elements.
+     * See <a href="#unmodifiable">Unmodifiable Sets</a> for details.
      *
      * @param <E> the {@code Set}'s element type
      * @param e1 the first element
@@ -484,8 +485,8 @@
     }
 
     /**
-     * Returns an immutable set containing three elements.
-     * See <a href="#immutable">Immutable Set Static Factory Methods</a> for details.
+     * Returns an unmodifiable set containing three elements.
+     * See <a href="#unmodifiable">Unmodifiable Sets</a> for details.
      *
      * @param <E> the {@code Set}'s element type
      * @param e1 the first element
@@ -502,8 +503,8 @@
     }
 
     /**
-     * Returns an immutable set containing four elements.
-     * See <a href="#immutable">Immutable Set Static Factory Methods</a> for details.
+     * Returns an unmodifiable set containing four elements.
+     * See <a href="#unmodifiable">Unmodifiable Sets</a> for details.
      *
      * @param <E> the {@code Set}'s element type
      * @param e1 the first element
@@ -521,8 +522,8 @@
     }
 
     /**
-     * Returns an immutable set containing five elements.
-     * See <a href="#immutable">Immutable Set Static Factory Methods</a> for details.
+     * Returns an unmodifiable set containing five elements.
+     * See <a href="#unmodifiable">Unmodifiable Sets</a> for details.
      *
      * @param <E> the {@code Set}'s element type
      * @param e1 the first element
@@ -541,8 +542,8 @@
     }
 
     /**
-     * Returns an immutable set containing six elements.
-     * See <a href="#immutable">Immutable Set Static Factory Methods</a> for details.
+     * Returns an unmodifiable set containing six elements.
+     * See <a href="#unmodifiable">Unmodifiable Sets</a> for details.
      *
      * @param <E> the {@code Set}'s element type
      * @param e1 the first element
@@ -563,8 +564,8 @@
     }
 
     /**
-     * Returns an immutable set containing seven elements.
-     * See <a href="#immutable">Immutable Set Static Factory Methods</a> for details.
+     * Returns an unmodifiable set containing seven elements.
+     * See <a href="#unmodifiable">Unmodifiable Sets</a> for details.
      *
      * @param <E> the {@code Set}'s element type
      * @param e1 the first element
@@ -586,8 +587,8 @@
     }
 
     /**
-     * Returns an immutable set containing eight elements.
-     * See <a href="#immutable">Immutable Set Static Factory Methods</a> for details.
+     * Returns an unmodifiable set containing eight elements.
+     * See <a href="#unmodifiable">Unmodifiable Sets</a> for details.
      *
      * @param <E> the {@code Set}'s element type
      * @param e1 the first element
@@ -610,8 +611,8 @@
     }
 
     /**
-     * Returns an immutable set containing nine elements.
-     * See <a href="#immutable">Immutable Set Static Factory Methods</a> for details.
+     * Returns an unmodifiable set containing nine elements.
+     * See <a href="#unmodifiable">Unmodifiable Sets</a> for details.
      *
      * @param <E> the {@code Set}'s element type
      * @param e1 the first element
@@ -635,8 +636,8 @@
     }
 
     /**
-     * Returns an immutable set containing ten elements.
-     * See <a href="#immutable">Immutable Set Static Factory Methods</a> for details.
+     * Returns an unmodifiable set containing ten elements.
+     * See <a href="#unmodifiable">Unmodifiable Sets</a> for details.
      *
      * @param <E> the {@code Set}'s element type
      * @param e1 the first element
@@ -661,8 +662,8 @@
     }
 
     /**
-     * Returns an immutable set containing an arbitrary number of elements.
-     * See <a href="#immutable">Immutable Set Static Factory Methods</a> for details.
+     * Returns an unmodifiable set containing an arbitrary number of elements.
+     * See <a href="#unmodifiable">Unmodifiable Sets</a> for details.
      *
      * @apiNote
      * This method also accepts a single array as an argument. The element type of
@@ -700,4 +701,26 @@
                 return new ImmutableCollections.SetN<>(elements);
         }
     }
+
+    /**
+     * Returns an unmodifiable Set containing the elements of the given Collection.
+     * Duplicate elements are permitted. If the Collection has a defined iteration order,
+     * the first element of any duplicates is preserved, and the rest are discarded.
+     * Otherwise, an arbitrary element is preserved.
+     * See <a href="#unmodifiable">Unmodifiable Sets</a> for
+     * information about the characteristics of the returned Set.
+     *
+     * @param <E> the {@code Set}'s element type
+     * @param coll the collection from which elements are drawn
+     * @return the new Set
+     * @since 10
+     */
+    @SuppressWarnings("unchecked")
+    static <E> Set<E> copyOf(Collection<? extends E> coll) {
+        if (coll instanceof ImmutableCollections.AbstractImmutableSet) {
+            return (Set<E>)coll;
+        } else {
+            return (Set<E>)Set.of(coll.stream().distinct().toArray());
+        }
+    }
 }