Do not consider flushed pages while regenerating field's value.

Author: ars18wrw

kernel/src/main/java/com/itextpdf/kernel/pdf/annot/PdfAnnotation.java

@@ -424,10 +424,12 @@ public PdfPage getPage() {
             } else {
                 for (int i = 1; i <= doc.getNumberOfPages(); i++) {
                     PdfPage docPage = doc.getPage(i);
-                    for (PdfAnnotation annot : docPage.getAnnotations()) {
-                        if (annotationIndirectReference.equals(annot.getPdfObject().getIndirectReference())) {
-                            page = docPage;
-                            break;
+                    if (!docPage.isFlushed()) {
+                        for (PdfAnnotation annot : docPage.getAnnotations()) {
+                            if (annotationIndirectReference.equals(annot.getPdfObject().getIndirectReference())) {
+                                page = docPage;
+                                break;
+                            }
                         }
                     }
                 }