HTTP Status 500 -

java.lang.NullPointerException
	java.util.ComparableTimSort.countRunAndMakeAscending(ComparableTimSort.java:320)
	java.util.ComparableTimSort.sort(ComparableTimSort.java:188)
	java.util.Arrays.sort(Arrays.java:1246)
	com.imooc.util.CheckUtil.checkSignature(CheckUtil.java:13)
	com.imooc.servlet.WeixinServlet.doGet(WeixinServlet.java:33)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:624)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
	org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)