code: public Object call(Iterable coll, Closure c) {
          List<Object> listContent = new ArrayList<Object>();
          if (coll != null) {
              for (Object it : coll) {
                  listContent.add(JsonDelegate.curryDelegateAndGetContent(c, it));
              }
          }
          content = listContent;
  
          return content;
      }
docs: A collection and closure passed to a JSON builder will create a root JSON array applying
  the closure to each object in the collection
  <p>
  Example:
  <pre><code class="groovyTestCase">
  class Author {
  String name
  }
  def authors = [new Author (name: "Guillaume"), new Author (name: "Jochen"), new Author (name: "Paul")]
  
  def json = new groovy.json.JsonBuilder()
  json authors, { Author author {@code ->}
  name author.name
  }
  
  assert json.toString() == '[{"name":"Guillaume"},{"name":"Jochen"},{"name":"Paul"}]'
  </code></pre>
  @param coll a collection
  @param c a closure used to convert the objects of coll
  @return a list of values