Not really java 7

[nodefourtytwo]

You claim that this container brings java 7, but:

~ % docker run -it --entrypoint="/bin/bash" thefactory/java
root@ddeeade95aa3:/# java -version
java version "1.6.0_32"
OpenJDK Runtime Environment (IcedTea6 1.13.4) (6b32-1.13.4-1~deb7u1)
OpenJDK 64-Bit Server VM (build 23.25-b01, mixed mode)

Java 7 is rightfully installed though. It's just not the default.
I recommend adding update-java-alternatives -s java-1.7.0-openjdk-amd64 to the Dockerfile