Upgrade rxjava2 2.1.6

Author: slandelle

pom.xml

@@ -387,7 +387,7 @@
 		<reactive-streams.version>1.0.0</reactive-streams.version>
 		<netty-reactive-streams.version>2.0.0</netty-reactive-streams.version>
 		<rxjava.version>1.3.2</rxjava.version>
-		<rxjava2.version>2.1.4</rxjava2.version>
+		<rxjava2.version>2.1.6</rxjava2.version>
 		<logback.version>1.2.3</logback.version>
 		<testng.version>6.11</testng.version>
 		<jetty.version>9.4.7.v20170914</jetty.version>