Setting synchrony.proxy.enabled=true when behind a reverse proxy does not enable synchrony-proxy

Summary

When Confluence is running behind a reverse proxy and the proxy settings are added to the server.xml file, the internal synchrony-proxy is automatically disabled. Following the Reverse Proxy with Internal Synchronyproxy documentation steps does not prevent the internal proxy from being disabled:

To turn on the Synchrony proxy:

1. Edit <home-directory>/confluence.cfg.xml
2. Set synchrony.proxy.enabled to true and save the file. 
   {code}<property name="synchrony.proxy.enabled">true</property>
   {code}
3. Restart Confluence for the changes to take effect. 

Environment

• Confluence running behind a reverse proxy (Apache, NGINX or IIS)
• Requests proxied to the internal synchrony-proxy instead of directly to synchrony

Steps to Reproduce

1. Configure the proxy settings to point to the synchrony-proxy as in the documentation
2. Make sure that the synchrony.proxy.enabled property is set to true in confluence.cfg.xml

Expected Results

Internal synchrony-proxy is enabled.

Actual Results

Internal synchrony-proxy is disabled automatically by the following step of the startup procedure: 

2017-01-05 17:52:28,404 INFO [ListenableFutureAdapter-thread-2] [plugins.synchrony.utils.TomcatConfigHelper] getProxyPort Checking if Tomcat is running behind a reverse proxy in C:\Program Files\Atlassian\Confluence\conf\server.xml... 

Notes

This is a major issue when terminating SSL at Tomcat and running Confluence behind a reverse proxy, as synchrony does not accept direct HTTPS connections.

Workaround

Add the following system property and restart Confluence:

CATALINA_OPTS="-Dsynchrony.proxy.enabled=true ${CATALINA_OPTS}"