I was coded the following lines for other purpose, when I observed a weird thing. The class of q is class org.apache.lucene.document.IntPoint$1, but I really can't find it in the doc.
Query q = IntPoint.newExactQuery("year", 2147483647);
System.out.println(q.getClass()); # this line prints out "class org.apache.lucene.document.IntPoint$1"