RFR: 8300866: Declare some classes final in java.io

[Alan Bateman]

On Mon, 23 Jan 2023 14:40:50 GMT, Per Minborg <pminborg at openjdk.org> wrote:

> This PR proposes declaring some internal classes in java.io as `final`, explicitly indicating that they are not intended for sub-classing. 
> 
> If you think declaring classes final is just "static noice", please see http://minborgsjavapot.blogspot.com/2021/12/why-general-inheritance-is-flawed-and.html first and then come back and comment on the issue.

Look okay. We should probably think about removing ExpiringCache as it hasn't been used for many releases.

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Marked as reviewed by alanb (Reviewer).

PR: https://git.openjdk.org/jdk/pull/12141