### Question:
FieldName implements Serializable { static String marshal(FieldName name){ if(name == null){ return null; } return name.getValue(); } FieldName(String value); FieldName intern(); @Override int hashCode(); @Override boolean equals(Object object); @Override String toString(); String getValue(); static FieldName create(String value);  }### Answer:
@Test public void marshal(){ assertEquals("x", FieldName.marshal(FieldName.create("x"))); assertEquals(null, FieldName.marshal(null)); }