### Question:
Relation { public void setId(Long id) { this.id = id; }  Long getId(); void setId(Long id); Long getSource(); void setSource(Long source); Long getTarget(); void setTarget(Long target); String getRelateType(); void setRelateType(String relateType);  }### Answer:
@Test public void testRelation() { Relation relation = new Relation(); relation.setId(0L); }