java.lang.IllegalArgumentException: geometries must not contain null elements

MultiPolygon multipolygon = geometryFactory.createMultiPolygon(polygons)//报错

polygons里包含空元素？？

参考：http://javadox.com/com.vividsolutions/jts/1.13/com/vividsolutions/jts/geom/LinearRing.html

例子：[[[1,2],[],[3,4]],[[],[]]]