Results 2 issues of afreetgo

**Description:** I used storm + siddhi to process monitoring data, but NullPointerException appeared. Detailed debugging screenshots are as follows: ![image](https://user-images.githubusercontent.com/3366292/56874610-9678f600-6a6d-11e9-9ad7-3222768501c4.png) ![image](https://user-images.githubusercontent.com/3366292/56874614-9d076d80-6a6d-11e9-8c59-28fd53f58c92.png) **Affected Siddhi Version:3.1.x,3.2.x

type/bug
priority/high

master doc display: com.github.Jasonchenlijian:FastBle:2.4.0 tag 2.3.4 doc display: compile 'com.clj.fastble:FastBleLib:2.3.4' Which one do you use? www.jitpack.io : com.github.Jasonchenlijian:FastBle:2.4.0 https://developer.aliyun.com/mvn/search : com.clj.fastble:FastBleLib:2.3.4