code: public XML addAttributes(Class<?> aClass,Attribute[] attributes){
  		checksAttributesExistence(aClass,attributes);
  		
  		for (Attribute attribute : attributes) {
  			if(attributeExists(aClass,attribute)) Error.xmlAttributeExistent(this.xmlPath,attribute, aClass);
  			findXmlClass(aClass).attributes.add(Converter.toXmlAttribute(attribute));
  		}
  		return this;
  	}
docs: This method adds the attributes to an existing Class.
  @param aClass class to which add attributes
  @param attributes attributes to add
  @return this instance of XML