Upgrade to jackson-dataformat-xml 2.8.4

Changelog:

https://github.com/FasterXML/jackson-dataformat-xml/blob/master/release-notes/VERSION

pom.xml

@@ -312,7 +312,7 @@
     <dependency>
       <groupId>com.fasterxml.jackson.dataformat</groupId>
       <artifactId>jackson-dataformat-xml</artifactId>
-      <version>2.7.3</version>
+      <version>2.8.4</version>
     </dependency>
     <dependency>
       <groupId>commons-fileupload</groupId>