Steps to Reproduce:

1. Created an application link between Confluence 5.5.3 and JIRA.
2. Try following URL:
   • <Confluence-URL>/plugins/servlet/applinks/proxy?appId=<APP-ID>&path=<JIRA-URL>/rest/api/latest/serverInfo
   1. Try above URL with JIRA Macros 5.5.4 and following is my result:
   2. Upgraded JIRA Macros to 5.6.3 and try above mentioned URL. Following is the result:
3. Following appears in my log file:

   2014-09-19 14:42:44,138 ERROR [http-bio-80-exec-11] [[Standalone].[localhost].[/].[servlet-module-container-servlet]] log Servlet.service() for servlet [servlet-module-container-servlet] in context with path [] threw exception
   java.lang.NullPointerException
   	at com.atlassian.confluence.plugins.jira.AbstractProxyServlet.doProxy(AbstractProxyServlet.java:119)
   	at com.atlassian.confluence.plugins.jira.AppLinksProxyRequestServlet.doProxy(AppLinksProxyRequestServlet.java:75)
   	at com.atlassian.confluence.plugins.jira.AbstractProxyServlet.doGet(AbstractProxyServlet.java:46)
   	at javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
   	at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
   	at com.atlassian.plugin.servlet.DelegatingPluginServlet.service(DelegatingPluginServlet.java:42)
   	at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
   	at com.atlassian.plugin.servlet.ServletModuleContainerServlet.service(ServletModuleContainerServlet.java:52)
   	at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
   ...
   	at com.atlassian.core.filters.AbstractHttpFilter.doFilter(AbstractHttpFilter.java:31)
   	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
   	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
   	at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312)
   	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
   	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
   	at java.lang.Thread.run(Thread.java:744)
   

   Expected Result:

   

   Actual Result: