https://docs.oracle.com/javase/8/docs/api/java/util/Spliterator.html
SIZED Characteristic value signifying that the value returned from
estimateSize() prior to traversal or splitting represents a finite
size that,in the absence of structural source modification,
represents an exact count of the number of elements that would be
encountered by a complete traversal.SUBSIZED Characteristic value signifying that all Spliterators
resulting from trySplit() will be both SIZED and SUBSIZED.
>是否存在SIZED标志打开但SUBSIZED标志关闭的情况?
>是否存在SUBSIZED标志打开但SIZED标志关闭的情况?