Summary

Specify the default implementation of java.net.URLStreamHandler.openConnection(URL,Proxy).

Problem

The current default implementation of openConnection(URL,Proxy) simply throws UnsupportedOperationException. Pedantically, this violates its own specification, since it does not throw IllegalArgumentException when passed a null value.

Solution

Update and specify the default implementation. Trivially, perform null argument checking, and subsequently throw UnsupportedOperationException ( since the URL stream handler implementation can realistically do nothing more ).

Specification

  /*
   * Same as openConnection(URL), except that the connection will be
   * made through the specified proxy; Protocol handlers that do not
   * support proxying will ignore the proxy parameter and make a
   * normal connection.
   *
   * Calling this method preempts the system's default
   * {@link java.net.ProxySelector ProxySelector} settings.
   *
+  * @implSpec
+  * The default implementation of this method first checks that the given
+  * {code URL} and {code Proxy} are not null, then throws {@code
+  * UnsupportedOperationException}. Subclasses should override this method
+  * with an appropriate implementation.
+  *
   * @param      u   the URL that this connects to.
   * @param      p   the proxy through which the connection will be made.
   *                 If direct connection is desired, Proxy.NO_PROXY
   *                 should be specified.
   * @return     a {@code URLConnection} object for the {@code URL}.
   * @exception  IOException  if an I/O error occurs while opening the
   *               connection.
   * @exception  IllegalArgumentException if either u or p is null,
   *               or p has the wrong type.
   * @exception  UnsupportedOperationException if the subclass that
   *               implements the protocol doesn't support this method.
   * @since      1.5
   */
  protected URLConnection openConnection(URL u, Proxy p) throws IOException