/usr/share/tomcat7/lib/commons-pool.jar is in tomcat7-common 7.0.28-4+deb7u4.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/tomcat7/lib/../../java/commons-pool.jar
/usr/share/tomcat7/lib/../../java/commons-pool.jar