The copyright header format check was introduced in JDK-8346046. However, a user recently reported that the check doesn't catch incorrect copyright headers in this pr(https://github.com/openjdk/jdk/pull/23550).

After investigation, I found that the issue was caused by the file regex in .jcheck/conf. There is a redundant "|" character after ".*\.jar".

files=^(?!LICENSE|license\.txt|.*\.bin|.*\.gif|.*\.jpg|.*\.png|.*\.icon|.*\.tiff|.*\.dat|.*\.patch|.*\.wav|.*\.class|.*-header|.*\.jar|).*

This redundant "|" prevents the regex from matching any string.