Upgrade to Jersey 2.21

Closes gh-3875

spring-boot-dependencies/pom.xml

@@ -94,7 +94,7 @@
 		<jaybird.version>2.2.8</jaybird.version>
 		<jdom2.version>2.0.6</jdom2.version>
 		<jedis.version>2.7.3</jedis.version>
-		<jersey.version>2.19</jersey.version>
+		<jersey.version>2.21</jersey.version>
 		<jetty.version>9.2.13.v20150730</jetty.version>
 		<jetty-jsp.version>2.2.0.v201112011158</jetty-jsp.version>
 		<jmustache.version>1.10</jmustache.version>