Guarding a static element with a non-static element may result in excessive concurrency, multiple threads may be able to access the guarded field simultaneously by locking in different object contexts.

Example:

    private ReadWriteLock lock = new ReentrantReadWriteLock();

    @GuardedBy("lock")
    public static void bar() {
        // ...
    }

Supported @GuardedBy annotations are:

• net.jcip.annotations.GuardedBy
• javax.annotation.concurrent.GuardedBy
• org.apache.http.annotation.GuardedBy
• com.android.annotations.concurrency.GuardedBy
• androidx.annotation.GuardedBy
• com.google.errorprone.annotations.concurrent.GuardedBy