Getting 400 error or 415 error when posting JSON to spring controller

When I post a JSON string to my spring controller, I get a 400 status error. My method takes in a @RequestBody parameter and when that is removed the method works.

Here is the controller:

@RequestMapping(value = "/events/idp", method = RequestMethod.POST)
public String receiveIDPEvents(@RequestBody Event event) throws JAXBException, JMSException, NamingException {
    System.out.println(event);
    return "Success!";
}

Here is the JSON being posted:

angular.module('hello', [])

.controller('navigation', function($rootScope, $scope, $http, $location) {
    $scope.Event= '{"cause": "test3", "location": "test"}';
    $http({
        method: 'POST',
        url: '/events/idp',
        data: $scope.Event,
        headers: {'Content-Type': 'application/x-www-form-urlencoded'}
    }).success(function(data) {$scope.name = data;}).error(function(data) {$scope.name = data;});
});

Here is the Event class:

public class Event {

    private String cause;


    /**
     * @return the cause
     */
    public String getCause() {
        return cause;
    }


    /**
     * @param cause the cause to set
     */
    public void setCause(String cause) {
        this.cause = cause;
    }


    /**
     * @return the location
     */
    public String getLocation() {
        return location;
    }


    /**
     * @param location the location to set
     */
    public void setLocation(String location) {
        this.location = location;
    }

    private String location;

    public Event(String cause, String location) {
        this.cause = cause;
        this.location = location;
    }

    public Event() {
    }
}

Another thing to note is that when I try to change the content type header to "application/json" I get a 415 unsupported media type error. I've tried a couple dozen solutions, but nothing resolves it.

Also, i've used the below code and the Event object is created perfectly:

ObjectMapper mapper=new ObjectMapper();
String json="{\"cause\": \"test3\", \"location\": \"test\"}";
Event event2 = mapper.readValue(json, Event.class);