Findbugs SIO_SUPERFLUOUS_INSTANCEOF

|| 在我的findbugs报告中，以下代码部分中有SIO_SUPERFLUOUS_INSTANCEOF正确性错误

/** Allow Comparison based on User-Labels */
public int compareTo(AbstractListItem o) {
    if ( !( o instanceof AbstractListItem ) ) {
        // Correctness - Unnecessary type check done using instanceof operator
        // : Method com.x.y.gui.topology.TopologyListNode.compareTo (AbstractListItem) 
        // does an unnecessary type check using instanceof operator when it 
        // can be determined statically
    return -1;
}

静态确定类型的正确方法是什么？