### Question:
DataDogIdentifier { @Override public int hashCode () { int result = key.hashCode(); result = 31 * result + value.hashCode(); return result; } private  DataDogIdentifier(); static DataDogIdentifier dataDogIdentifier(); @Override int hashCode(); @Override boolean equals(Object o); String getKey(); String getValue(); DataDogIdentifier withKey(String key); DataDogIdentifier withValue(String value); @Override String toString();  }### Answer:
@Test public void testHashCode () { assertEquals(identifier.hashCode(), identifier.hashCode()); assertNotEquals(identifier.hashCode(), secondIdentifier.hashCode()); }