RFR: JDK-8232279: Improve test helpers #2

[Alexander Matveev]

Looks good.

On 10/15/2019 12:13 PM, Alexey Semenyuk wrote:
> Please review the jpackage fix for bug [1] at [2].
>
> This is a fix for the JDK-8200758-branch branch of the open sandbox 
> repository (jpackage).
>
> Additionally migrated some tests that used the old test helpers to use 
> the new test helpers.
>
> - Alexey
>
> [1] https://bugs.openjdk.java.net/browse/JDK-8232279
>
> [2] http://cr.openjdk.java.net/~asemenyuk/8232279/webrev.00/
>