This property represents the "Kids" entry of the name tree node
It is defined as part of the PDF 1.0 specification.
An Array containing child NameTreeNodeElements which may be intermediate
or leaf nodes.
This entry is always null in leaf nodes. In intermediate nodes
it must always be non-null.
In the root node either this entry or the EntryNames entry should be non-null. But
For definitive details see:.
The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 36,