No worries, still think that the Spring in Action would be worth reading (I'm going to do so).
The certification books tend to cover a lot of material quickly as the exam is (well was) based on a lot of subjects. The exam guide is to be found here;
spring developer certification exam. I've just had a quick look at the new exam subjects and it looks like they have dropped the older technologies (like; XML configuration [yuk], JMX, RMI,
SOAP) and added some more relevant newer ones like spring boot, and spring data.