Make vertx request header case insensitive

[Malandril]

Description

Make vertx http request's header case insensitive to fix case related issues.

Fixes #6917

Type of change

• Bug fix (non-breaking change which fixes an issue)
• Feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change
• Chore (non-breaking change which doesn't affect codebase;
  test, version modification, documentation, etc.)

Checklist

• Code contributed by me aligns with current project license: Apache 2.0
• I Added CHANGELOG entry regarding this change
• I have implemented unit tests to cover my changes
• I have added/updated the javadocs and other documentation accordingly
• No new bugs, code smells, etc. in SonarCloud report
• I tested my code in Kubernetes
• I tested my code in OpenShift

[shawkins]

@manusa do you also want to make the standard impl case-insensitive?

[manusa]

@manusa do you also want to make the standard impl case-insensitive?

Headers should be case-insensitive. Also, HTTP >1 keys should usually be lower-cased AFAIR.

I remember dealing with this in the past (probably when implementing the StandardHttpClient or the TestHttpClient).
Haven't dug into the current issue yet, I'm not sure what might have caused it.

[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
84.2% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[manusa]

LGTM, thx!