Fix link to Spring Framework javadoc

Author: wilkinsona

build.gradle

@@ -37,7 +37,7 @@ ext {
 springVersion = '4.2.5.RELEASE'
 javadocLinks = [
 'http://docs.oracle.com/javase/8/docs/api/',
-'http://docs.spring.io/spring-framework/docs/$springVersion/javadoc-api/',
+"http://docs.spring.io/spring-framework/docs/$springVersion/javadoc-api/",
 'https://docs.jboss.org/hibernate/stable/beanvalidation/api/',
 'https://docs.jboss.org/hibernate/stable/validator/api/'
 ] as String[]