RFR: 8323746: Add PathElement hashCode and equals

[Maurizio Cimadamore]

On Wed, 31 Jan 2024 13:04:07 GMT, Per Minborg <pminborg at openjdk.org> wrote:

> This PR proposes to implement `hashCode()` and `equals()` methods for implementations of `PathElement`.
> 
> In doing so, the previous `PathElementImpl` was removed and replaced in favor of distinct `record` implementations, each reflecting its own path element selection type. This also allowed the `PathKind` to be removed as this piece of information is now carried in the sealed type hierarchy. 
> 
> It is worth noting, the implementations resides in the `jdk.internal` package and consequently, they are not exposed to clients. So, we could use pattern matching (for example) internally but not in client code.

src/java.base/share/classes/jdk/internal/foreign/LayoutPath.java line 454:

> 452:     }
> 453: 
> 454:     public static final class SequenceElement

Why are these not empty records?

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PR Review Comment: https://git.openjdk.org/jdk/pull/17651#discussion_r1473276715