Method addAttribute

sdk_unuse/PostParameters.java:419–422

`attr`=`value` @param attr value @return this

(String attr, String value)

	 * @return this
	 */
	public PostParameters addAttribute(String attr, String value) {
		addString(attr, value);
		return this;
	}
	
	private void addString(String id, String str) {
		try {