Log4j memory leak via Classloader

We have a memory leak in the application. If we stop and run Jetty in the loop in JUnit we get OOM. 

The issue is in the following lines. I think Log4j attaches an object to the thread via the get method (because the field is defined like this:

private static final ThreadLocal<DefaultLogBuilder> logBuilder = ThreadLocal.withInitial(DefaultLogBuilder::new);

It means that Log4j attaches an object to a thread even Constants.ENABLE_THREADLOCALS is disabled. My thoughts:

1) Log4j code attaches DefaultLogBuilder object to threads
2) DefaultLogBuilder object has a link to DefaultLogBuilder.class that has a link to DefaultLogBuilder.class.getClassloader() 

3) DefaultLogBuilder.class.getClassloader() is a Web App Classloader and during our JUnit testing many classes are loaded to the classloader
4) I suspect somewhere some Thread Pool is used and even if we clean all resources in the application, Log4j holds classloaders and all loaded classes via DefaultLogBuilder.class.getClassloader()
 
I suggest checking Constants.ENABLE_THREADLOCALS variable before calling logBuilder.get() in org.apache.logging.log4j.spi.AbstractLogger. After the following changes, the problem is gone. (except additionally I added log4j2.disable.jmx=true, because it has a similar issue, but I think it is not a log4j issue)

/**
 * Returns a log builder that logs at the specified level.
 *
 * @since 2.20.0
 */
protected LogBuilder getLogBuilder(Level level) {
    if (Constants.ENABLE_THREADLOCALS) {
        DefaultLogBuilder builder = logBuilder.get();
        if (!builder.isInUse()) {
            return builder.reset(this, level);
        }
    }
    return new DefaultLogBuilder(this, level);
} 

Original code:

/**
 * Returns a log builder that logs at the specified level.
 *
 * @since 2.20.0
 */
protected LogBuilder getLogBuilder(Level level) {
    DefaultLogBuilder builder = logBuilder.get();
    return Constants.ENABLE_THREADLOCALS && !builder.isInUse() ? builder.reset(this, level)
            : new DefaultLogBuilder(this, level);
} 

P.S. Please, if it is possible can you include the fix in an upcoming release, the issue randomly happens during our application build and it is a headache for us Thank you.

P.S.S. We use a free license of Yourkit for open-source projects. Please, look at the picture from a profiler.