Update xstream dependency (#1479)

Author: trask

core/build.gradle

@@ -71,7 +71,7 @@ dependencies {
     compile ([group: 'commons-io', name: 'commons-io', version: '2.6' ])
     compile ([group: 'org.apache.commons', name: 'commons-lang3', version: '3.7'])
     compile ([group: 'org.apache.httpcomponents', name: 'httpclient', version: '4.5.3'])
-    compile ([group: 'com.thoughtworks.xstream', name: 'xstream', version: '1.4.11.1'])
+    compile ([group: 'com.thoughtworks.xstream', name: 'xstream', version: '1.4.15'])
     compile ([group: 'com.google.code.gson', name: 'gson', version: '2.8.2'])
     // update transitive dependency version
     compile ([group: 'com.google.guava', name: 'guava', version: '27.1-android'])

gradle.properties

@@ -1,4 +1,4 @@
 // Project properties
-version=2.6.2
+version=2.6.3-BETA
 group=com.microsoft.azure