Add final & sealed to jdk.internal.reflect

[wenshao]

I have discussed with @liach that we can improve the code of jdk.internal by adding final and sealed.

I will submit a series of PRs to do this, and this is one of them, jdk.internal.reflect

Adding final allows JIT to do more optimization and remove virtual function calls. Adding sealed makes the inheritance system clearer, and JIT may also make optimizations in the future.

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Progress

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Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk.git pull/24900/head:pull/24900
$ git checkout pull/24900

Update a local copy of the PR:
$ git checkout pull/24900
$ git pull https://git.openjdk.org/jdk.git pull/24900/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 24900

View PR using the GUI difftool:
$ git pr show -t 24900

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk/pull/24900.diff

[bridgekeeper]

👋 Welcome back swen! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

❗ This change is not yet ready to be integrated.
See the Progress checklist in the description for automated requirements.

[openjdk]

@wenshao The following labels will be automatically applied to this pull request:

• core-libs
• hotspot-runtime

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[wenshao]

/label remove hotspot-runtime

[openjdk]

@wenshao
The hotspot-runtime label was successfully removed.