RFR: 8290313: Produce warning when user specified java.io.tmpdir directory doesn't exist [v4]

[Sean Coffey]

On Fri, 18 Nov 2022 18:36:51 GMT, Weibing Xiao <duke at openjdk.org> wrote:

>> print warning message for java.io.tmpdir when it is set through the command line and the value is not good for creating file folder.
>
> Weibing Xiao has updated the pull request incrementally with one additional commit since the last revision:
> 
>   updated from the review comment

src/java.base/share/classes/java/lang/System.java line 2247:

> 2245:         Unsafe.getUnsafe().ensureClassInitialized(StringConcatFactory.class);
> 2246: 
> 2247:         // Emit a warning if java.io.tmpdir is set via the command line to a directory that doesn't exist

could you split this comment across 2 lines ? - Keeps length similar to comment just above this code.

test/jdk/java/io/File/TempDirDoesNotExist.java line 30:

> 28:  */
> 29: 
> 30: import jdk.test.lib.Platform;

unused import

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PR: https://git.openjdk.org/jdk/pull/11174