Bump log4j version

Author: rmstar

pom.xml

@@ -88,7 +88,7 @@
     <es-hadoop.version>7.6.2</es-hadoop.version>
     <slf4j.version>1.7.5</slf4j.version>
     <netty.version>4.0.30.Final</netty.version>
-    <log4j.version>2.7</log4j.version>
+    <log4j.version>2.16.0</log4j.version>
     <logback.version>1.1.7</logback.version>
     <commons.version>3.1</commons.version>
     <junit.version>4.11</junit.version>