### Question:
ForEachExpression extends ArrayUpdateExpression { @Override public JsonNode toJson() { ObjectNode node = getFactory().objectNode(); ObjectNode opNode = getFactory().objectNode(); opNode.set(field.toString(), query.toJson()); opNode.set("$update", update.toJson()); node.set("$foreach", opNode); return node; } ForEachExpression(Path field, QueryExpression query, UpdateExpression update); Path getField(); QueryExpression getQuery(); UpdateExpression getUpdate(); @Override JsonNode toJson(); static ForEachExpression fromJson(ObjectNode node); @Override int hashCode(); @Override boolean equals(Object obj);  }### Answer:
@Test @Ignore public void testToJson() { ForEachExpression instance = null; JsonNode expResult = null; JsonNode result = instance.toJson(); assertEquals(expResult, result); }