RFR JMC-4262: Duplicate headers when copying thread dump text to clipboard

[Alex Macdonald]

Hi Jie,

On Thu, Sep 19, 2019 at 9:08 AM Jie Kang <jkang at redhat.com> wrote:

> Hi all,
>
> Please review this attempt to address JMC-4262. Within the constraints
> of the user's selection being an ordered list, I came up with this
> solution. Please let me know what you think!
>

The functionality of this patch looks good to me.

A couple nits:
- Eclipse is highlighting a warning for lines 415 & 416 having to do with
HashSet not being parameterized
- At line 414 the @SuppressWarnings("Unchecked") was there because of the
unchecked cast, but `parents` is now an empty hashset so it isn't required
anymore


>
> Webrev: http://cr.openjdk.java.net/~jkang/jmc-4262/webrev.01/
> Bug: https://bugs.openjdk.java.net/browse/JMC-4262
>
>
> Regards,
>
>
Cheers,

Alex