8250244: Address reliance on default constructors in java.net

Reviewed-by: alanb, vtewari

src/java.base/share/classes/java/net/Authenticator.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2016, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2020, Oracle and/or its affiliates. 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
@@ -74,6 +74,11 @@ class Authenticator {
     private RequestorType requestingAuthType;
     private final String key = AuthenticatorKeys.computeKey(this);
 
+    /**
+     * Constructor for subclasses to call.
+     */
+    public Authenticator() {}
+
     /**
      * The type of the entity requesting authentication.
      *

src/java.base/share/classes/java/net/CacheRequest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2003, 2004, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 2020, Oracle and/or its affiliates. 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
@@ -43,6 +43,11 @@ import java.io.IOException;
  */
 public abstract class CacheRequest {
 
+    /**
+     * Constructor for subclasses to call.
+     */
+    public CacheRequest() {}
+
     /**
      * Returns an OutputStream to which the response body can be
      * written.

src/java.base/share/classes/java/net/CacheResponse.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2003, 2004, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 2020, Oracle and/or its affiliates. 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
@@ -41,6 +41,11 @@ import java.io.IOException;
  */
 public abstract class CacheResponse {
 
+    /**
+     * Constructor for subclasses to call.
+     */
+    public CacheResponse() {}
+
     /**
      * Returns the response headers as a Map.
      *

src/java.base/share/classes/java/net/ContentHandler.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1995, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1995, 2020, Oracle and/or its affiliates. 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
@@ -83,6 +83,11 @@ import java.io.IOException;
  */
 public abstract class ContentHandler {
 
+    /**
+     * Constructor for subclasses to call.
+     */
+    public ContentHandler() {}
+
     /**
      * Given a URL connect stream positioned at the beginning of the
      * representation of an object, this method reads that stream and

src/java.base/share/classes/java/net/CookieHandler.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 2020, Oracle and/or its affiliates. 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
@@ -50,6 +50,11 @@ import sun.security.util.SecurityConstants;
  * @since 1.5
  */
 public abstract class CookieHandler {
+    /**
+     * Constructor for subclasses to call.
+     */
+    public CookieHandler() {}
+
     /**
      * The system-wide cookie handler that will apply cookies to the
      * request headers and manage cookies from the response headers.

src/java.base/share/classes/java/net/DatagramSocketImpl.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1996, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1996, 2020, Oracle and/or its affiliates. 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
@@ -57,6 +57,11 @@ import java.util.Set;
 
 public abstract class DatagramSocketImpl implements SocketOptions {
 
+    /**
+     * Constructor for subclasses to call.
+     */
+    public DatagramSocketImpl() {}
+
     /**
      * The local port number.
      */

src/java.base/share/classes/java/net/ProxySelector.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2003, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 2020, Oracle and/or its affiliates. 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
@@ -80,6 +80,11 @@ public abstract class ProxySelector {
         }
     }
 
+    /**
+     * Constructor for subclasses to call.
+     */
+    public ProxySelector() {}
+
     /**
      * Gets the system-wide proxy selector.
      *

src/java.base/share/classes/java/net/ResponseCache.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 2020, Oracle and/or its affiliates. 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
@@ -60,6 +60,11 @@ import sun.security.util.SecurityConstants;
  */
 public abstract class ResponseCache {
 
+    /**
+     * Constructor for subclasses to call.
+     */
+    public ResponseCache() {}
+
     /**
      * The system wide cache that provides access to a url
      * caching mechanism.

src/java.base/share/classes/java/net/SecureCacheResponse.java

@@ -39,6 +39,11 @@ import java.util.Optional;
  * @since 1.5
  */
 public abstract class SecureCacheResponse extends CacheResponse {
+    /**
+     * Constructor for subclasses to call.
+     */
+    public SecureCacheResponse() {}
+
     /**
      * Returns the cipher suite in use on the original connection that
      * retrieved the network resource.

src/java.base/share/classes/java/net/SocketAddress.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2000, 2020, Oracle and/or its affiliates. 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
@@ -43,4 +43,8 @@ public abstract class SocketAddress implements java.io.Serializable {
     @java.io.Serial
     static final long serialVersionUID = 5215720748342549866L;
 
+    /**
+     * Constructor for subclasses to call.
+     */
+    public SocketAddress() {}
 }

src/java.base/share/classes/java/net/URLDecoder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1998, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1998, 2020, Oracle and/or its affiliates. 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
@@ -81,6 +81,12 @@ import java.util.Objects;
 
 public class URLDecoder {
 
+    /**
+     * Do not call.
+     */
+    @Deprecated(since="16", forRemoval=true)
+    public URLDecoder() {}
+
     // The platform default encoding
     static String dfltEncName = URLEncoder.dfltEncName;
 

src/java.base/share/classes/java/net/URLStreamHandler.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1995, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1995, 2020, Oracle and/or its affiliates. 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
@@ -51,6 +51,11 @@ import sun.net.www.ParseUtil;
  * @since   1.0
  */
 public abstract class URLStreamHandler {
+    /**
+     * Constructor for subclasses to call.
+     */
+    public URLStreamHandler() {}
+
     /**
      * Opens a connection to the object referenced by the
      * {@code URL} argument.