Java 7 entered it's "end of public updates" earlier this year (April 2015). While it looks like ongoing support will be provided by RedHat (for OpenJDK 7 at least) , and Java 7 is not entirely EOL , we should look to update to Java 8 support for DSpace.
-  RedHat taking over OpenJDK7: http://www.infoworld.com/article/2938303/java/red-hat-takes-the-reins-for-openjdk-7.html
-  Spring describes why Java 7 is not entirely EOL yet: https://spring.io/blog/2015/04/01/ongoing-support-for-java-7-and-even-java-6
DSpace needs to be fully tested with Java 8 to see whether there are any issues. Feel free to any Java 8 issues to this ticket as they are discovered.