/usr/lib/jvm/java-6-openjdk-amd64/jre/lib/jar.binfmt is in openjdk-6-jre-headless 6b38-1.13.10-1~deb7u1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 | package openjdk-6
interpreter /usr/bin/jexec
magic PK\x03\x04
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