public boolean isLeader() {
        return this.fsm.isLeader();
    }
Set priority value, required for priority-based election, it must be a positive value when
enable the feature, some special value meaning:
<ul>
<li>-1 : disable priority-based election.</li>
<li>0: will never participate in election.</li>
<li>1: minimum value</li>
</ul>
value.
jraft-example/src/main/java/com/alipay/sofa/jraft/example/priorityelection/PriorityElectionNode.java