* ❶ by wrapping thread factory using method {@link com.alibaba.ttl.threadpool.TtlExecutors#getDisableInheritableThreadFactory(java.util.concurrent.ThreadFactory)} / {@link com.alibaba.ttl.threadpool.TtlForkJoinPoolHelper#getDefaultDisableInheritableForkJoinWorkerThreadFactory()}
* for thread pooling components({@link java.util.concurrent.ThreadPoolExecutor}, {@link java.util.concurrent.ForkJoinPool}).
* Inheritable feature in thread pooling components should <b>never</b> happen,
* because threads in thread pooling components is pre-created and pooled, these threads is neutral for biz logic/data.
* <br>
* You can turn on "disable inheritable for thread pool" by {@link com.alibaba.ttl.threadpool.agent.TtlAgent}
* so as to wrap thread factory for thread pooling components({@link java.util.concurrent.ThreadPoolExecutor}, {@link java.util.concurrent.ForkJoinPool})
* automatically and transparently.
* <p>
* 2) or by {@link com.alibaba.ttl.threadpool.DisableInheritableThreadFactory}, {@link com.alibaba.ttl.threadpool.DisableInheritableForkJoinWorkerThreadFactory}
* ❷ or by overriding method {@link #childValue(Object)}.
* Whether the value should be inheritable or not can be controlled by the data owner,
* disable it <b>carefully</b> when data owner have a clear idea.
* <pre> {@code TransmittableThreadLocal<String> transmittableThreadLocal = new TransmittableThreadLocal<String>() {