RFR: Fix NullPointerException on a parallel run [v3]

[Dmitry Bessonov]

On Thu, 1 Sep 2022 01:26:36 GMT, Dmitry Bessonov <dbessono at openjdk.org> wrote:

>> If `null` is a possibility, check for it.
>> 
>> ?? I don't understand the concern about referencing a different constructor that has been around since the beginning of Java time, and why it is better to do string arithmetic to construct a file path.
>
> Implicitly checking for `null` here below. 
> If we could keep the existing approaches and API calls in the legacy code base, let's not pull anything new without necessity. I guess we don't have necessity to call an API that is new to this context.
> 
> 
> processFile("".equals(path) // Zero length string if the node is a root
>     ? new File(filesToScan[i]) 
>     : new File(path + File.separator + filesToScan[i]));

If needed, refactoring like `File` constructors call optimizations deserves to be better done with a separate commit.

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PR: https://git.openjdk.org/jtharness/pull/35