The class com.jcraft.jsch.jcraft.Compression is missing from the
/usr/share/java/jsch.jar. This class allows the integration with JZlib to
enable the compression during the SSH sessions. This class is not compiled
because jzlib.jar is not on the classpath at build time (and the package
doesn't depend on libjzlib-java).
This is the maintainer address of Debian's Java team
debian-j...@lists.debian.org for discussions and questions.