Получено, как показано ниже BaseFont font = BaseFont.createFont (BaseFont.HELVETICA, BaseFont.CP1252, BaseFont.EMBEDDED);
AcroFields fields = stamper.getAcroFields();
for (String key : fields.getFields().keySet()) {
if (!values.containsKey(key)) {
System.out.println("Value not found for:" + key);
continue;
}
fields.setFieldProperty(key, "textsize", 4f, null);
fields.setFieldProperty(key, "textfont", font, null);
fields.setField(key, values.get(key));
fields.regenerateField(key);
}