code: function(json){
    
    // Protect against forgetting the new keyword when calling the constructor
    if(!(this instanceof AtomCommon)){
      return new AtomCommon(json);
    }
    
    // If the given object is already an instance then just return it. DON'T copy it.
    if(AtomCommon.isInstance(json)){
      return json;
    }
    
    this.init(json);
  }
docs: Common attributes for all Atom entities
  
  @see {@link https://tools.ietf.org/html/rfc4287#page-7|RFC 4287}
  
  @class AtomCommon
  @extends Base
  @param {Object} [json]