Update log4j version to 1.2.16

Change-Id: I0667ff861fc12a45df136198bac72f16827d98c5
diff --git a/pom.xml b/pom.xml
index 95964f6..aadcc79 100644
--- a/pom.xml
+++ b/pom.xml
@@ -600,7 +600,7 @@
       <dependency>
         <groupId>log4j</groupId>
         <artifactId>log4j</artifactId>
-        <version>1.2.15</version>
+        <version>1.2.16</version>
         <exclusions>
           <exclusion>
             <groupId>javax.mail</groupId>