title: Removing empty entry from json or object
body: <p>I am using angular 2 with a datatable to modify a large data set. After the modification I need to save the changes in my database using a spring.</p>
  
  <p>this is the json that I send to the server.</p>
  
  <pre><code>{  
    "id":3,
    "mois":"2017-07-01",
    "status":"Soumise",
    "ligneNoteDeFrais":{  
      "2017-07-10":{  
        "id":1,
        "day":"2017-07-10",
        "fk":{  
          "id":2,
          "description":"frais kilomtrique",
          "nb":5,
          "pu":6,
          "totale":44,
            "typeNoteDeFrais":null
          },
          "preuves":[],
          "detailFrais":{  
            "12":{  
              "id":1,
              "description":"test",
              "nb":5,
              "pu":4,
              "totale":0,
              "typeNoteDeFrais":{  
              "id":12,
              "intitule":"gg",
              "justifiable":true,
              "justificationObligatoire":true,
              "quantifiable":true,
              "new":false
            }
          },
          "14":{ },
          "15":{ },
          "18":{ },
          "19":{ }
        }
      },
      "2017-07-01":{  
        "fk":{ },
        "detailFrais":{  
          "12":{ },
          "14":{ },
          "15":{ },
          "18":{ },
          "19":{ }
        }
      },
      "2017-07-02":{  
        "fk":{ },
        "detailFrais":{  
          "12":{ },
          "14":{ },
          "15":{ },
          "18":{ },
          "19":{ }
        }
      }
    }
  }
  </code></pre>
  
  <p>As you can see there are some empty entrie in this JSON</p>
  
  <p>Is there a solution to delete these entrie before sending them to the server or so that they are not mapped in the object.</p>