private Segment<T> getLast() {
        if (!this.segments.isEmpty()) {
            return this.segments.peekLast();
        }
        return null;
    }
A recyclable segment.
@author boyan(boyan@antfin.com)

@param <T>
jraft-core/src/main/java/com/alipay/sofa/jraft/util/SegmentList.java