We might not be able to use org.apache.logging.log4j.core.config.plugins.util.TypeConverters.PatternConverter if we want to support the int flag for java.util.regex.Pattern.compile(String, int).
It seems the solution is to change org.apache.logging.log4j.core.filter.RegexFilter.createFilter(Pattern, Boolean, Result, Result) and either:
- Add an int parameter and let user compute the flag themselves, or
- Add a String parameter and allow users to say things like "CASE_INSENSITIVE | MULTILINE" but that means parsing such things.
Perhaps we should just start with an int flag.