title: Jackson Json accesing JsonNode property name
body: <p>I have a schema like this:</p>
  
  <pre><code>{
    "type" : "object",
    "$schema" : "http://json-schema.org/draft-03/schema#",
    "id" : "urn:jsonschema:com:vlashel:dto:UserDto",
    "description" : "this is the top description",
    "title" : "this is the top title",
    "properties" : {
      "number" : {
        "type" : "integer"
        "required" : true
      },
      "password" : {
        "type" : "string"
        "required" : true
  
      }
  }
  </code></pre>
  
  <p>I have the following code that converts this shcema draft 3 to draft 4 by removing "required", I want to collect nodes property names that have 'requred' in them. How do I do that? I don't see methods for this..</p>
  
  <pre><code>             JsonNode jsonNode = jsonNodeIterator.next();
              ObjectNode element;
              if (jsonNode instanceof ObjectNode) {
                  element = (ObjectNode) jsonNode;
                  element.remove("required");
                 String propertyName = element.getPropertyName(); //I'm looking for this kind of method.
  </code></pre>
  
  <p>Thanks!</p>