empty fields should not be added in the final schema. 

**Description** 
Empty fields are being included into the final schema, whish shouldn't be. 
For example I only create a label with only `name` parameter then the json should like this ` {
  "name": "code"
 }` but it is looking like this ` {
  "name": "code",
  "alias": ""
 }`. 
