@UnstableApi
    public static Sampler<? super RequestContext> requestContextLeakDetectionSampler() {
        return REQUEST_CONTEXT_LEAK_DETECTION_SAMPLER;
    }
Returns the {@link Sampler} that determines whether to trace the stack trace of request contexts leaks
and how frequently to keeps stack trace. A sampled exception will have the stack trace while the others
will have an empty stack trace to eliminate the cost of capturing the stack trace.

<p>The default value of this flag is {@link Sampler#never()}.
Specify the {@code -Dcom.linecorp.armeria.requestContextLeakDetectionSampler=<specification>} JVM option
to override the default. This feature is disabled if {@link Sampler#never()} is specified.
See {@link Sampler#of(String)} for the specification string format.</p>
core/src/main/java/com/linecorp/armeria/common/Flags.java