This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
The object pushed onto the stack is a MapEntry, according to the entrySet() Javadocs. A MapEntry has "key" and "value" properties. The "value" property is the object stored in the map. You're printing the "value" property--I'm not sure what you expected.