PDFBOX-5660: improve comments

git-svn-id: https://svn.apache.org/repos/asf/pdfbox/trunk@1923984 13f79535-47bb-0310-9956-ffa450edef68

Author: THausherr

pdfbox/src/main/java/org/apache/pdfbox/pdmodel/interactive/form/PDAcroForm.java

@@ -260,6 +260,7 @@ public void flatten(List<PDField> fields, boolean refreshAppearances) throws IOE
         // preserve all non widget annotations
         for (PDPage page : pages)
         {
+            // get the widgets that are to be flattened for this page
             Set<COSDictionary> widgetsForPageMap = pagesWidgetsMap.get(page.getCOSObject());
 
             // indicates if the original content stream
@@ -760,7 +761,8 @@ private Rectangle2D getTransformedAppearanceBBox(PDAppearanceStream appearanceSt
     }
 
     /**
-     * Build a map of pages => widgets
+     * Build a map of page => set of widgets to be flattened
+     *
      * @param fields a list of fields to be flattened
      * @param pages the page tree
      * @return