PDFBOX-5660: add check, as suggested by Valery Bokov; closes #231

git-svn-id: https://svn.apache.org/repos/asf/pdfbox/trunk@1928112 13f79535-47bb-0310-9956-ffa450edef68

Author: THausherr

pdfbox/src/main/java/org/apache/pdfbox/multipdf/Splitter.java

@@ -657,14 +657,18 @@ public void setStartPage(int start)
      * This will set the end page.
      *
      * @param end the 1-based end page
-     * @throws IllegalArgumentException if the end page is smaller than one.
+     * @throws IllegalArgumentException if the end page is smaller than one or than the start page.
      */
     public void setEndPage(int end)
     {
         if(end <= 0)
         {
             throw new IllegalArgumentException("End page is smaller than one");
         }
+        if (end < startPage)
+        {
+            throw new IllegalArgumentException("End page is smaller than startPage");
+        }
         endPage = end;
     }