RFR: 8297778: Modernize and improve module jdk.sctp

[Daniel Fuchs]

On Tue, 29 Nov 2022 16:46:43 GMT, Per Minborg <pminborg at openjdk.org> wrote:

> This PR proposes a variety of modernisations to the `jdk.sctp` module.
> 
> During the fix of https://bugs.openjdk.org/browse/JDK-8296024, several improvement areas were identified including: 
> 
> * Replacing duplicate code segments 
> * Making certain fields final 
> * Using enhanced switch 
> * Using records 
> * Fixing typos 
> * Marking fields participating in serialisation with `@Serial` 
> * Modernizing toString() implementations 
> * Using pattern matching 
> * Using diamond operators

It is a bit unusual to use a local class as a holder class (the typical manner is to a have a private static final nested class) but we didn't have local classes until recently - so maybe that's OK. I assume there's only one version of that class and it is static?

src/jdk.sctp/share/classes/sun/nio/ch/sctp/SctpStdSocketOption.java line 32:

> 30: public record SctpStdSocketOption<T>(String name,
> 31:                                      Class<T> type,
> 32:                                      int constValue)

This changes the implementation of `toString`, `equals` and `hashCode`. Have you verified that it is OK to do so?

src/jdk.sctp/unix/classes/sun/nio/ch/sctp/SctpMultiChannelImpl.java line 33:

> 31: import java.io.FileDescriptor;
> 32: import java.io.IOException;
> 33: import java.util.*;

It would be better to avoid wildcards in regular imports.

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PR: https://git.openjdk.org/jdk/pull/11418