/usr/share/tomcat7/lib/servlet-api.jar is in tomcat7-common 7.0.52-1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/tomcat7/lib/../../java/tomcat-servlet-api-3.0.jar
/usr/share/tomcat7/lib/../../java/tomcat-servlet-api-3.0.jar