[foreign-memaccess+abi] RFR: Remove dead code, add tests and fixes [v2]

[Jorn Vernee]

On Tue, 14 Feb 2023 13:56:43 GMT, Per Minborg <pminborg at openjdk.org> wrote:

>> This PR suggests removing dead code and addition of some tests. Also, a fix for zero-length mapped segment is added. It is anticipated this special zero-length segment is going to be removed in a separate PR.
>
> Per Minborg has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - Fix copyright years
>  - Remove zero-length fixes and more

test/jdk/java/foreign/TestByteBuffer.java line 319:

> 317:     public void testMappedSegmentAsByteBuffer() throws Throwable {
> 318:         File f = new File("test4.out");
> 319:         assert f.createNewFile();

I suggest just using `assertTrue` here, rather than `assert`. Technically this will always work since we run the tests with assertions enabled, but it looks a little bit fishy to depend on a side-effect from an `assert`.

test/jdk/java/foreign/TestSegmentAllocators.java line 240:

> 238:                 assertThrows(UnsupportedOperationException.class, segment::isLoaded);
> 239:                 assertThrows(UnsupportedOperationException.class, segment::force);
> 240:                 assertEquals(segment.isMapped(), segment instanceof MappedMemorySegmentImpl);

Isn't the actual value always false? Why not use `assertFalse`?

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PR: https://git.openjdk.org/panama-foreign/pull/792