// declare simple variable
VariableField simpleVariableField = Fields.createSimpleVariableField(doc, "test_simple_variable");
Assert.assertNotNull(simpleVariableField);
TextSpanElement newTextSpanElement = doc.newParagraph("Update Simple Variable Field:").newTextSpanElement();
simpleVariableField.updateField("simple variable content", newTextSpanElement);
newTextSpanElement = doc.newParagraph("Show Simple Variable Field:").newTextSpanElement();
simpleVariableField.displayField(newTextSpanElement);
// declare user variable
VariableField userVariableField = Fields.createUserVariableField(doc, "test_user_variable", "test");
Assert.assertNotNull(userVariableField);