At first, this issue looks like a duplicate of https://issues.jenkins-ci.org/browse/JENKINS-42618, but the difference here is the signature (object array instead of string):

org.jenkinsci.plugins.scriptsecurity.sandbox.RejectedAccessException: Scripts not permitted to use staticMethod org.codehaus.groovy.runtime.DefaultGroovyMethods getAt java.lang.Object[] groovy.lang.IntRange

The offending line:

version.split(/\./)[0..2]

 Where version is a string. It seems like the split converts the string to an object array.