The Bundle-RequiredExecutionEnvironment changed in 3.6.5.Final from J2SE-1.6 to Java2SE-1.7.

The list of supported execution environments depends on the container, but these are supported more or less everywhere: http://www.osgi.org/Specifications/Reference

J2SE-1.6 wasn't on the list either, but it worked with Apache Felix. Java2SE-1.7 doesn't work, so it should be replaced with the standard JavaSE-1.7.