--- old/src/share/classes/java/util/function/DoubleBinaryOperator.java	2012-12-05 09:51:07.914804466 -0800
+++ new/src/share/classes/java/util/function/DoubleBinaryOperator.java	2012-12-05 09:51:07.706804456 -0800
@@ -27,12 +27,27 @@
 /**
  * An operation on two {@code double} operands yielding a {@code double} result.
  *
+ * <p>This is the primitive type specialization of {@link BinaryOperator} for
+ * {@code double} and also may be used as a {@code BinaryOperator<Double>}. When
+ * used as a {@code BinaryOperator} the default {@code operate} implementation
+ * provided by this interface neither accepts null parameters nor does it return
+ * null results.
+ *
  * @since 1.8
  */
-public interface DoubleBinaryOperator /* extends BinaryOperator<Double> */ {
-//
-//    @Override
-//    public default Double operate(Double left, Double right) { return operateAsDouble((double) left, (double) right); }
+public interface DoubleBinaryOperator extends BinaryOperator<Double> {
+
+    /**
+     * {@inheritDoc}
+     *
+     * @param left {@inheritDoc}, must be non-null
+     * @param right {@inheritDoc}, must be non-null
+     * @return {@inheritDoc}, always non-null
+     */
+    @Override
+    public default Double operate(Double left, Double right) {
+        return operateAsDouble((double)left, (double)right);
+    }
 
     /**
      * Returns the {@code double} result of the operation upon the
@@ -40,7 +55,7 @@
      * {@code right} for operations where the order of parameters matters.
      *
      * @param left the left operand value
-     * @param right  the right operand value
+     * @param right the right operand value
      * @return the result of the operation
      */
     public double operateAsDouble(double left, double right);