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extend "sasl.kerberos.principal.to.local.rules"  config rule format/syntax by supporting an optional  "/L" (toLowerCase) at the end of the rule. However, it must be noted that this does not affect how pattern matches on input and therefore that will still be case-sensitive. 

 For example, given the rules

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If the source string is joe-qa-cl1/host@EXAMPLE.COM, the result will isbe joe-qa
If the source string is JOE-QA-cl1/host@EXAMPLE.COM, the result will isbe joe-qa-upper
If the source string is joe_user/host@EXAMPLE.COM, the result will isbe joe_user
If the source string is JOE_USER/host@EXAMPLE.COM, the result iswill be joe_use

However, it must be noted that this does not affect how pattern matches on input and therefore that will still be case-sensitive.

Compatibility, Deprecation, and Migration Plan

• This is an extension to the existing sasl.kerberos.principal.to.local.rules format and there will be no impact on existing users.

Rejected Alternatives

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• .