Remove instantiation of com.sun.jndi.ldap.LdapCtxFactory for JDK16+ compatibility

[famod]

Resolves #17092

The following change in Spring led me to try out removing it and lo and behold, it worked: spring-projects/spring-ldap#568

See #8651 and #8696 for more context of that instantiation.

Not sure who can review this... @sberyozkin maybe? Or @galderz?

[famod]

Not entirely sure about backporting to 2.0.1 but I'm leaning towards yes.

[gsmet]

I think this needs to be carefully verified as the initial issue was a corner case.

[famod]

Ah I see! I finally found the right PR that introduced this: #9486 (#8696 was not merged back then)

@gsmet I assume there is no test coverage for that corner case in this repo?

[gsmet]

I think it fails with the tests we have... given you have the right tool to build the native images. I wouldn't be surprised if the issue is only with Mandrel.

@zakkak any chance you could help here? Maybe run this PR with Mandrel releases?

[zakkak]

I think it fails with the tests we have... given you have the right tool to build the native images. I wouldn't be surprised if the issue is only with Mandrel.

@zakkak any chance you could help here? Maybe run this PR with Mandrel releases?

@gsmet I am not sure how I can help. It appears like this patch is to resolve a JDK16+ compatibility issue. I have no way to verify this since we are not yet building/testing Mandrel for JDK 16+. Would a test using Mandrel 21.1 (JDK11 based) suffice?

[famod]

@zakkak I think a JDK 11 based Mandrel test would cover Guillaume's concerns.

[zakkak]

@zakkak I think a JDK 11 based Mandrel test would cover Guillaume's concerns.

OK, I started the following two:

• Mandrel 21.1: https://github.com/graalvm/mandrel/actions/runs/1022639598
• Mandrel 20.3: https://github.com/graalvm/mandrel/actions/runs/1022639971

[gsmet]

@zakkak yeah that's exactly what I wanted. This workaround was added for Mandrel so if we want to remove it, we need to make sure it's not an issue anymore.

[zakkak]

@gsmet both Mandrel 20.3 and 21.1 runs passed :)

[gsmet]

OK, let's do it then. Thanks @zakkak for checking!