public void setValue(PDSignature value) throws IOException
    {
        getCOSObject().setItem(COSName.V, value);
        applyChange();
    }
@Test
    void setValueForAbstractedSignatureField()
    {
        PDSignatureField sigField = new PDSignatureField(acroForm);
        sigField.setPartialName("SignatureField");
        assertThrows(UnsupportedOperationException.class, () -> {
            sigField.setValue("Can't set value using String");
        });
    }