src/java.base/share/classes/sun/net/util/ProxyUtil.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
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package sun.net.util;

import sun.net.ApplicationProxy;

import java.net.Proxy;

public final class ProxyUtil {

    private ProxyUtil() {}

    /**
     * Creates a new {@link Proxy} instance for the given proxy iff it is
     * neither null, {@link Proxy#NO_PROXY Proxy.NO_PROXY}, an
     * {@link ApplicationProxy} instance, nor already a {@code Proxy} instance.
     */
    public static Proxy copyProxy(Proxy proxy) {
        return proxy == null
                || proxy.getClass() == Proxy.class
                || proxy instanceof ApplicationProxy
                ? proxy
                : new Proxy(proxy.type(), proxy.address());
    }

}