RFR: 8258422: Cleanup unnecessary null comparison before instanceof check in java.base [v3]

[Aleksei Efimov]

On Wed, 16 Dec 2020 09:44:37 GMT, Chris Hegarty <chegar at openjdk.org> wrote:

>> Andrey Turbanov has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   8258422: Cleanup unnecessary null comparison before instanceof check in java.base
>>   use instanceof pattern matching in UnixPath too
>
> Let's take advantage of "flow scoping" to eliminate some of these casts. A few examples follow.

Hi Andrey,

Could you, please, also take a look at `java.net.Socket`:
java/net/Socket.java:        if (bindpoint != null && (!(bindpoint instanceof InetSocketAddress)))
java/net/Socket.java-            throw new IllegalArgumentException("Unsupported address type");
And `HttpURLConnection`:
    sun/net/www/protocol/http/HttpURLConnection.java:                    if (a != null && c instanceof HttpURLConnection) {
    sun/net/www/protocol/http/HttpURLConnection.java-                        ((HttpURLConnection)c).setAuthenticator(a);
The following cmd was used to find them: `rgrep -A 1 "= null .* instanceof "`

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PR: https://git.openjdk.java.net/jdk/pull/20