DesignForExtension check crashes CheckStyle if an undocumented non-final method is present in a record (Java 14 + Java 15)

[vovkss]

Check documentation: https://checkstyle.sourceforge.io/config_design.html#DesignForExtension

/var/tmp $ javac WhatsThis.java --enable-preview --release=15
Note: WhatsThis.java uses preview language features.
Note: Recompile with -Xlint:preview for details.


/var/tmp $ cat config.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE module PUBLIC "-//Checkstyle//DTD Checkstyle Configuration 1.3//EN" "https://checkstyle.org/dtds/configuration_1_3.dtd">
<module name="Checker">
  <module name="TreeWalker">
    <module name="DesignForExtension"/>
  </module>
</module>


/var/tmp $ cat WhatsThis.java
public record WhatsThis(
    String whatever
) {
    @Override
    public String toString() {
        return "Whatever " + whatever;
    }
}


/var/tmp $ RUN_LOCALE="-Duser.language=en -Duser.country=US"
/var/tmp $ java $RUN_LOCALE -jar checkstyle-8.36-all.jar -c config.xml WhatsThis.java
Starting audit...
com.puppycrawl.tools.checkstyle.api.CheckstyleException: Exception was thrown while processing WhatsThis.java
        at com.puppycrawl.tools.checkstyle.Checker.processFiles(Checker.java:311)
        at com.puppycrawl.tools.checkstyle.Checker.process(Checker.java:221)
        at com.puppycrawl.tools.checkstyle.Main.runCheckstyle(Main.java:408)
        at com.puppycrawl.tools.checkstyle.Main.runCli(Main.java:331)
        at com.puppycrawl.tools.checkstyle.Main.execute(Main.java:190)
        at com.puppycrawl.tools.checkstyle.Main.main(Main.java:125)
Caused by: java.lang.NullPointerException: Cannot invoke "com.puppycrawl.tools.checkstyle.api.DetailAST.getType()" because "searchAST" is null
        at com.puppycrawl.tools.checkstyle.checks.design.DesignForExtensionCheck.getNearestClassOrEnumDefinition(DesignForExtensionCheck.java:437)
        at com.puppycrawl.tools.checkstyle.checks.design.DesignForExtensionCheck.visitToken(DesignForExtensionCheck.java:278)
        at com.puppycrawl.tools.checkstyle.TreeWalker.notifyVisit(TreeWalker.java:340)
        at com.puppycrawl.tools.checkstyle.TreeWalker.processIter(TreeWalker.java:451)
        at com.puppycrawl.tools.checkstyle.TreeWalker.walk(TreeWalker.java:278)
        at com.puppycrawl.tools.checkstyle.TreeWalker.processFiltered(TreeWalker.java:155)
        at com.puppycrawl.tools.checkstyle.api.AbstractFileSetCheck.process(AbstractFileSetCheck.java:87)
        at com.puppycrawl.tools.checkstyle.Checker.processFile(Checker.java:337)
        at com.puppycrawl.tools.checkstyle.Checker.processFiles(Checker.java:298)
        ... 5 more
Checkstyle ends with 1 errors.

---

Since records are implicitly final, the DesignForExtension check should ignore records completely.

[romani]

Fix is merged