[FLINK-12054][Tests] HBaseConnectorITCase fails on Java 9

[leesf]

What is the purpose of the change

Fix the error in HBaseConnectorITCase on Java 9.

Brief change log

Create a new URLClassLoader with directory.

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): (no)
• The public API, i.e., is any changed class annotated with @Public(Evolving): (no)
• The serializers: (no)
• The runtime per-record code paths (performance sensitive): (no)
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Yarn/Mesos, ZooKeeper: (no)
• The S3 file system connector: (no)

Documentation

• Does this pull request introduce a new feature? (no)
• If yes, how is the feature documented? (not documented)

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Review Progress

• ✅ 1. The [description] looks good.
  • Approved by @zentol [PMC]
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• ❓ 3. Needs [attention] from.
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[zentol]

@flinkbot approve description

[zentol]

The point of this method is to mutate the default classloader so that the hbase-site.xml is on the classpath later on.

By creating a new classloader that is immediately discarded once the method exists and never used to actually load anything this method becomes a no-op, which isn't acceptable.

[leesf]

@zentol hi, Chesnay. Sorry to bother you, could you please tell me the reason you closed this PR.

[zentol]

@leesf Your solution at the time did not fix the problem as I out-lined in my comment and you didn't respond to it. I now see that you made another attempt, but it yet again does not work. This is especially concerning since the very same comment on your first solution still applies to your second one.

Pull requests are not a public WIP branch, they are to be used for providing, at the very least, working solutions.
I closed the PR since I considered it unlikely that you will provide such a solution anytime soon. Your attempts indicate that you neither verified your solutions, nor truly understand the code you're changing.

Please go back to the JIRA, thoroughly analyze the problem, provide&discuss solutions and verify them, before opening another PR.