Upgrade to JMustache 1.16

Closes gh-976

Author: wilkinsona

gradle.properties

@@ -5,5 +5,5 @@ org.gradle.jvmargs=-Xmx2g -Dfile.encoding=UTF-8
 org.gradle.parallel=true
 
 javaFormatVersion=0.0.47
-jmustacheVersion=1.15
+jmustacheVersion=1.16
 springFrameworkVersion=7.0.0-M7