RFR: Fix deprecation warnings coming from JDK 16 [v2]

[Jonathan Gibbons]

On Mon, 5 Jul 2021 06:51:18 GMT, Sergei Ustimenko <github.com+5709644+fdesu at openjdk.org> wrote:

>> This PR fixes compilation warnings that fail builds during compilation because of -Werror flag.
>> The issues with compilation appear on JDK 16. Warnings that were fixed:
>> - warning: [missing-explicit-ctor] class JTRegModuleHelper in exported package java.lang declares no explicit constructors, thereby exposing a default constructor to clients of module java.base
>> - SimpleReporter.java:*: warning: [removal] Integer(int) in Integer has been deprecated and marked for removal 
>> 
>> After the changes build passes.
>
> Sergei Ustimenko has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Update copyrights

I created a JBS issue, https://bugs.openjdk.java.net/browse/CODETOOLS-7902991
The change looks OK, but note that the default build platform within Oracle is still JDK 8 and so the code must remain compilable by JDK 8 or with `--release 8`.

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PR: https://git.openjdk.java.net/jtreg/pull/15