6546639: (spec)javax.net.ssl.SSLContext.getInstance(null) throws undocumented NPE

Summary: add NullPointerException description to those methods.
Reviewed-by: weijun

src/share/classes/javax/net/ssl/SSLContext.java

 /*
- * Copyright 1999-2006 Sun Microsystems, Inc.  All Rights Reserved.
+ * Copyright 1999-2008 Sun Microsystems, Inc.  All Rights Reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -134,6 +134,7 @@ public class SSLContext {
      * @exception NoSuchAlgorithmException if no Provider supports a
      *          TrustManagerFactorySpi implementation for the
      *          specified protocol.
+     * @exception NullPointerException if protocol is null.
      *
      * @see java.security.Provider
      */
@@ -175,6 +176,7 @@ public class SSLContext {
      *          registered in the security provider list.
      *
      * @throws IllegalArgumentException if the provider name is null or empty.
+     * @throws NullPointerException if protocol is null.
      *
      * @see java.security.Provider
      */
@@ -210,6 +212,7 @@ public class SSLContext {
      *          from the specified Provider object.
      *
      * @throws IllegalArgumentException if the provider name is null.
+     * @throws NullPointerException if protocol is null.
      *
      * @see java.security.Provider
      */