Java 8: Compile error compiling CMS with Java 8

Building the CMS with Java 8 fails with the following error:

[INFO] -------------------------------------------------------------
[ERROR] COMPILATION ERROR :
[INFO] -------------------------------------------------------------
[ERROR] /var/lib/jenkins/workspace/cms-2.26.xx/api/src/main/java/org/hippoecm/frontend/model/map/AbstractValueMap.java:[466,26] error: incompatible types: inference variable T#1 has incompatible upper bounds Enum<T#2>,T#3
[INFO] 1 error

This might have been fixed (backported) in JDK8u40 planned for March 2015
https://bugs.openjdk.java.net/browse/JDK-8043926
http://stackoverflow.com/questions/23063474/why-does-this-java-8-program-not-compile
http://openjdk.java.net/projects/jdk8u/releases/8u40.html