Please refer to bugid 4988192.
As a workaround to bugid 4988192 the following solution was proposed by
the plugin team ...
ProxyInfo proxy = PluginProxyManager.getProxyInfo(url);
String proxyInfo = proxy.getProxy(); // get the host name
int port = proxy.getPort(); // get the port.

This solution works only when the PAC files points to proxy server (e.g
PROXY host:proxy).
However a PAC file can return "DIRECT" also.

If the PAC file points to "DIRECT" the proxy host returned should be
a string, like "DIRECT" and not null.