RFR: 8273484: Cleanup unnecessary null comparison before instanceof check in java.naming

[Aleksei Efimov]

On Mon, 6 Sep 2021 08:08:33 GMT, Andrey Turbanov <github.com+741251+turbanoff at openjdk.org> wrote:

> Update code checks both non-null and instance of a class in java.naming module classes.
> The checks and explicit casts could also be replaced with pattern matching for the instanceof operator.
> For example:
>     The following code:
> 
>         return (obj != null &&
>                 obj instanceof CompoundName &&
>                 impl.equals(((CompoundName)obj).impl));
> 
> 
> Can be simplified to:
>     
> 
>         return (obj instanceof CompoundName other) &&
>                 impl.equals(other.impl);
> 
> 
> See similar cleanup in java.base - https://bugs.openjdk.java.net/browse/JDK-8258422

Hi Andrey,
The changes look good to me.
And it looks like there is one more method to cleanup: [LdapReferralContext.setHopCount](https://github.com/openjdk/jdk/blob/master/src/java.naming/share/classes/com/sun/jndi/ldap/LdapReferralContext.java#L201)

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PR: https://git.openjdk.java.net/jdk/pull/5374