enemies.add("Dave");
    assertEquals(1, goodFriends.size());
    assertEquals(2, immut.size());
    assertEquals(2, mut.size());
  }

  public void testSymmetricDifference() {
    Set<String> friends = Sets.newHashSet("Tom", "Joe", "Dave");
    Set<String> enemies = Sets.newHashSet("Dick", "Harry", "Tom");

    enemies.add("Dave");
    assertEquals(1, goodFriends.size());
    assertEquals(2, immut.size());
    assertEquals(2, mut.size());
  }

  public void testSymmetricDifference() {
    Set<String> friends = Sets.newHashSet("Tom", "Joe", "Dave");
    Set<String> enemies = Sets.newHashSet("Dick", "Harry", "Tom");

```JSON
{
    "item": {
        "name": "Foo",
        "description": "The pretender",
        "price": 42.0,
        "tax": 3.2
    },
    "user": {
        "username": "dave",
        "full_name": "Dave Grohl"
    }
}
```

!!! note "Внимание"
    Обратите внимание, что хотя параметр `item` был объявлен таким же способом, как и раньше, теперь предпологается, что он находится внутри тела с ключом `item`.

        "bar"
    ],
    "images": [
        {
            "url": "http://example.com/baz.jpg",
            "name": "The Foo live"
        },
        {
            "url": "http://example.com/dave.jpg",
            "name": "The Baz"
        }
    ]
}
```

!!! info
    Beachten Sie, dass der `images`-Schlüssel jetzt eine Liste von Bild-Objekten hat.

## Tief verschachtelte Modelle

        "bar"
    ],
    "images": [
        {
            "url": "http://example.com/baz.jpg",
            "name": "The Foo live"
        },
        {
            "url": "http://example.com/dave.jpg",
            "name": "The Baz"
        }
    ]
}
```

!!! info "Информация"
    Заметьте, что теперь у ключа `images` есть список объектов изображений.

## Глубоко вложенные модели

// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

package cmd

import (
	"bytes"
	"context"
	"encoding/json"
	"errors"
	"fmt"

//     newerThan: "7d" # match objects newer than this value (e.g. 7d10h31s)
//     olderThan: "7d" # match objects older than this value (e.g. 7d10h31s)
//     createdAfter: "date" # match objects created after "date"
//     createdBefore: "date" # match objects created before "date"
//     tags:
//       - key: "name"
//         value: "pick*" # match objects with tag 'name', with all values starting with 'pick'
//     metadata:

    private var servedDate: Date? = null
    private var servedDateString: String? = null

    /** The last modified date of the cached response, if known. */
    private var lastModified: Date? = null
    private var lastModifiedString: String? = null

    /**
     * The expiration date of the cached response, if known. If both this field and the max age are

		if err != nil {
			return err
		}

		if p.Version == 0 {
			// This means that policy was in the old version (without any
			// timestamp info). We fetch the mod time of the file and save
			// that as create and update date.
			p.CreateDate = objInfo.ModTime
			p.UpdateDate = objInfo.ModTime
		}

		m[policy] = p
		return nil
	}
}

		canonicalHeaders += "\n"
	}

	date := expires // Date is set to expires date for presign operations.
	if date == "" {
		// If expires date is empty then request header Date is used.
		date = headers.Get(xhttp.Date)
	}

	// From the Amazon docs:
	//
	// StringToSign = HTTP-Verb + "\n" +
	// 	 Content-Md5 + "\n" +
	//	 Content-Type + "\n" +
	//	 Date/Expires + "\n" +
	//	 CanonicalizedProtocolHeaders +