### Question:
FieldNameAdapter extends XmlAdapter<String, FieldName> { @Override public FieldName unmarshal(String value){ return FieldName.create(value); }  @Override FieldName unmarshal(String value); @Override String marshal(FieldName value);  }### Answer:
@Test public void unmarshal(){ FieldNameAdapter adapter = new FieldNameAdapter(); try { adapter.unmarshal(null); fail(); } catch(NullPointerException npe){ } try { adapter.unmarshal(""); fail(); } catch(IllegalArgumentException iae){ } assertNotNull(adapter.unmarshal("x")); }