Angular, Java Service REST

I'm trying to persist (insert data) using AngularJS and WebService REST in Java, when I click Insert, the following error appears in the console:

  

POST link 415 (Unsupported Media Type).

What could it be?

// WEB.XML

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
         xmlns="http://java.sun.com/xml/ns/javaee" 
         xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" 
         xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" 
         id="WebApp_ID" 
         version="2.5">

  <!-- COMO DEFAULT, O NOME DO MEU PROJETO, ESSE NOME IRÁ APARECER NA URL -->
  <display-name>Cast_Frotas</display-name> 

  <!-- MAPEANDO O SERVLET-->
  <servlet> 
    <servlet-name>Jersey RESTfull</servlet-name>
    <servlet-class>org.glassfish.jersey.servlet.ServletContainer</servlet-class>

    <init-param>
      <param-name>jersey.config.server.provider.packages</param-name>
      <param-value>br.com.Cast_frotas.service</param-value>
    </init-param> 

    <load-on-startup>1</load-on-startup>
  </servlet>


  <servlet-mapping>
    <servlet-name>Jersey RESTfull</servlet-name>
    <url-pattern>/rest/*</url-pattern>
  </servlet-mapping>
</web-app>

// MY ANGULAR CONTROL

$scope.inserir = function (){
    $http.post(linkservice + "insert", $scope.curso).then(function(data){
        alert('Curso inserido com sucesso!');
    });
}

// COURSE CLASS

public class Curso {
    private int id;
    private String nome;
    private String descricao;

    public Curso() {

    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getNome() {
        return nome;
    }

    public void setNome(String nome) {
        this.nome = nome;
    }

    public String getDescricao() {
        return descricao;
    }

    public void setDescricao(String descricao) {
        this.descricao = descricao;
    }
}

// CLASS CtrlCURSO

public class CtrlCurso {

    public boolean insert(Curso c){ 
        return CursoDB.getInstance().insert(c); 
    }

    public List<Curso> getList(){   
        return CursoDB.getInstance().getListAll();  
    }
}

// MY SERVICE

@POST
@Path("/insert")
public void inserirCurso(Curso c){  
    new CtrlCurso().insert(c);
}