Revert java 17 compiler

[cecemei]

Description

• revert back to java 11 compiler for hadoop compatibility in root pom
• in embedded-test module, force use java 17 to support the multi-line string syntax, and exclude it from strict compilation.

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This PR has:

• been self-reviewed.
  • using the concurrency checklist (Remove this item if the PR doesn't have any relation to concurrency.)
• added documentation for new or modified features or behaviors.
• a release note entry in the PR description.
• added Javadocs for most classes and all non-trivial methods. Linked related entities via Javadoc links.
• added or updated version, license, or notice information in licenses.yaml
• added comments explaining the "why" and the intent of the code wherever would not be obvious for an unfamiliar reader.
• added unit tests or modified existing tests to cover new code paths, ensuring the threshold for code coverage is met.
• added integration tests.
• been tested in a test Druid cluster.

[clintropolis]

why is this needed? seems worth a comment

[jtuglu1]

Maybe:

Using JDK 11 language level restriction until Druid 37 which (as of 2025-12-10) is the current target for removing Hadoop support from the dev list threads. Hadoop relies upon JDK 8/11 language level which breaks when upgraded to anything higher.

from: #18759 (comment)

[cecemei]

Thanks all, I added some explanation.

[clintropolis]

we will also need to remember to remove the changes here and in static-checks.yml in the future, not sure how to best manage that debt, i guess we could put a note in the root pom.xml...

imo we should try to avoid diverging like this in any other modules and try to stay consistent with the root pom unless there is a seriously good reason so that we don't have to keep track of stuff like this.

[kfaraz]

I think we may fix it up in this patch itself. The only requirement for 17 (AFAIK) is the doc-style strings added in a recent test NestedDataFormatsTest. For the time being, we can just stick to regular strings.

[cecemei]

update the root pom to include things to check for upgrade to 17.

imo using 17 in embedded-test is safe and multi-line string syntax helps with readability a lot, so hopefully we dont let this java 11 thing drag up back.

[jtuglu1]

@cecemei good to merge?