FinalClass: If you follow the checkstyle hint, the code breaks.

[hneemann]

/var/tmp $ javac Foo.java
/var/tmp $ cat Foo.java

/**
 * Foo is a simple test.
 */
public final class Foo {

    /**
     * Test.
     */
    private class Test {

        /**
         * Create a new instance.
         */
        private Test() {
        }
    }

    /**
     * Test 2.
     */
    private class Test2 extends Test {
    }

}

/var/tmp $ cat digital_checks.xml

<?xml version="1.0"?>
<!DOCTYPE module PUBLIC
        "-//Puppy Crawl//DTD Check Configuration 1.2//EN"
        "http://www.puppycrawl.com/dtds/configuration_1_2.dtd">
<module name="Checker">
    <module name="TreeWalker">
        <module name="FinalClass"/>
    </module>
</module>

/var/tmp $ java -Duser.language=en -jar checkstyle-7.6-all.jar -c digital_checks.xml Foo.java

Starting audit...
[ERROR] /home/hneemann/temp/checkstyle/Foo.java:9: Class Test should be declared as final. [FinalClass]
Audit done.
Checkstyle ends with 1 errors.

---

The class Test can not be final because Test2 inherits from Test. There should be no error at all.
If you decare Test as final, the code does not compile anymore.

---

[romani]

connection with @unrealwork is lost, PR is closed as incomplete.
If smb want to continue from scratch or from where unrealwork is finished, please be welcome .

[linusjf]

https://groups.google.com/forum/m/#!msg/checkstyle/Szdb6677DWM/cCAH59EYAAAJ

Another example Java source that exhibits the above scenario.

[pbludov]

Will be fixed in #10859