351.4.

from("yammer:messages?consumerKey=aConsumerKey&consumerSecret=aConsumerSecretKey&accessToken=aAccessToken")
    .to("mock:result");

{
    "messages":[
        {
            "replied_to_id":null,
            "network_id":7654,
            "url":"https://www.yammer.com/api/v1/messages/305298242",
            "thread_id":305298242,
            "id":305298242,
            "message_type":"update",
            "chat_client_sequence":null,
            "body":{
                "parsed":"Testing yammer API...",
                "plain":"Testing yammer API...",
                "rich":"Testing yammer API..."
            },
            "client_url":"https://www.yammer.com/",
            "content_excerpt":"Testing yammer API...",
            "created_at":"2013/06/25 18:14:45 +0000",
            "client_type":"Web",
            "privacy":"public",
            "sender_type":"user",
            "liked_by":{
                "count":1,
                "names":[
                    {
                        "permalink":"janstey",
                        "full_name":"Jonathan Anstey",
                        "user_id":1499642294
                    }

                ]

            },
            "sender_id":1499642294,
            "language":null,
            "system_message":false,
            "attachments":[

            ],
            "direct_message":false,
            "web_url":"https://www.yammer.com/redhat.com/messages/305298242"
        },
        {
            "replied_to_id":null,
            "network_id":7654,
            "url":"https://www.yammer.com/api/v1/messages/294326302",
            "thread_id":294326302,
            "id":294326302,
            "message_type":"system",
            "chat_client_sequence":null,
            "body":{
                "parsed":"(Principal Software Engineer) has [[tag:14658]] the redhat.com network. Take a moment to welcome Jonathan.",
                "plain":"(Principal Software Engineer) has #joined the redhat.com network. Take a moment to welcome Jonathan.",
                "rich":"(Principal Software Engineer) has #joined the redhat.com network. Take a moment to welcome Jonathan."
            },
            "client_url":"https://www.yammer.com/",
            "content_excerpt":"(Principal Software Engineer) has #joined the redhat.com network. Take a moment to welcome Jonathan.",
            "created_at":"2013/05/10 19:08:29 +0000",
            "client_type":"Web",
            "sender_type":"user",
            "privacy":"public",
            "liked_by":{
                "count":0,
                "names":[

                ]

            }
        }
        ]

    }

Exchange exchange = mock.getExchanges().get(0);
Messages messages = exchange.getIn().getBody(Messages.class);

assertEquals(2, messages.getMessages().size());
assertEquals("Testing yammer API...", messages.getMessages().get(0).getBody().getPlain());
assertEquals("(Principal Software Engineer) has #joined the redhat.com network. Take a moment to welcome Jonathan.", messages.getMessages().get(1).getBody().getPlain());