Update to okhttp3:okhttp 3.14.9

Closes gh-238

gradle/dependency-management.gradle

@@ -32,7 +32,7 @@ dependencyManagement {
 		dependency 'org.assertj:assertj-core:3.18.1'
 		dependency 'org.mockito:mockito-core:3.6.28'
 		dependency "com.squareup.okhttp3:mockwebserver:3.14.9"
-		dependency "com.squareup.okhttp3:okhttp:3.+"
+		dependency "com.squareup.okhttp3:okhttp:3.14.9"
 		dependency "com.jayway.jsonpath:json-path:2.+"
 	}
 }