@Nullable
    @Override
    public <T extends RequestContext> T currentOrNull() {
        return delegate.currentOrNull();
    }
Creates a new instance.

@param delegate the underlying {@link RequestContextStorage} that stores {@link RequestContext}
@param sampler the {@link Sampler} that determines whether to retain the stacktrace of the context leaks
core/src/main/java/com/linecorp/armeria/internal/common/LeakTracingRequestContextStorage.java