@Test
public void clipField() {

    PDField field = PDFieldFactory.createFieldAddingChildToParent(new PDAcroForm(new PDDocument()), dictionary,
            null);
    assertTrue(SignatureClipper.clipSignature(field));
    assertFalse(field.getCOSObject().containsKey(COSName.V));
    assertFalse(field.getCOSObject().containsKey(COSName.SV));
    assertFalse(field.getCOSObject().containsKey(COSName.LOCK));
}