Upgrade to Gson 2.7

Closes gh-6281

spring-boot-dependencies/pom.xml

@@ -78,7 +78,7 @@
 		<glassfish-el.version>3.0.0</glassfish-el.version>
 		<gradle.version>1.12</gradle.version>
 		<groovy.version>2.4.7</groovy.version>
-		<gson.version>2.6.2</gson.version>
+		<gson.version>2.7</gson.version>
 		<h2.version>1.4.192</h2.version>
 		<hamcrest.version>1.3</hamcrest.version>
 		<hazelcast.version>3.6.4</hazelcast.version>