I tried to build without monitoring support, the build was successful.
compile "org.apereo.cas:cas-server-support-ldap:${casServerVersion}"
compile "org.apereo.cas:cas-server-support-monitor:${casServerVersion}"
# Versions
cas.version=6.2.0-RC1-SNAPSHOT
springBootVersion=2.2.0.RELEASE
# Use -jetty, -undertow to other containers
# Or blank if you want to deploy to an external container
appServer=-tomcat
executable=false
gradleVersion=5.6.3
tomcatVersion=9.0.27