public ThreadGroup getThreadGroup() {
        return group;
    }
This is a ThreadFactory which assigns threads based the strategies provided.

If no strategies are provided AffinityStrategies.ANY is used.

@author jiachun.fjc
jraft-rheakv/rheakv-core/src/main/java/com/alipay/sofa/jraft/rhea/util/concurrent/AffinityNamedThreadFactory.java