[java] case insensitive header names in http requests

[iampopovich]

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Description

I opened PR with initial changes. i have already asked some questions about feature in feature request ticket I will implement new tests as soon as I get more information about task details

Motivation and Context

according to #12697 I started to discover how to implement this feature

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• [x] I have read the contributing document.
• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [ ] I have added tests to cover my changes.
• [ ] All new and existing tests passed.

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PR Type

Enhancement

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Description

• Normalize header names to lowercase in setHeader method to ensure case-insensitive handling.
• Normalize header names to lowercase in addHeader method to ensure case-insensitive handling.

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Changes walkthrough 📝

	Relevant files
Enhancement	HttpMessage.java Normalize header names to lowercase in HTTP message handling. java/src/org/openqa/selenium/remote/http/HttpMessage.java Convert header names to lowercase in setHeader method. Convert header names to lowercase in addHeader method. +2/-2

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