### Question:
ArrayAddExpression extends ArrayUpdateExpression { @Override public int hashCode() { int hash = 7; hash = 89 * hash + Objects.hashCode(this.values); hash = 89 * hash + Objects.hashCode(this.op); hash = 89 * hash + Objects.hashCode(this.field); return hash; } ArrayAddExpression(Path field, UpdateOperator op, List<RValueExpression> list); Path getField(); List<RValueExpression> getValues(); UpdateOperator getOp(); @Override JsonNode toJson(); static ArrayAddExpression fromJson(ObjectNode node); @Override int hashCode(); @Override boolean equals(Object obj);  }### Answer:
@Test public void testHashCode() { assertEquals(new ArrayAddExpression(Path.EMPTY, UpdateOperator._set, null).hashCode(), new ArrayAddExpression(Path.EMPTY, UpdateOperator._set, null).hashCode()); }