Get the next version and replace the version name in the summary (post create successor and link)

JIRA updateNextVersionInSummary.groovy

import com.atlassian.jira.ComponentManager
import com.atlassian.jira.user.ApplicationUser;
import com.atlassian.jira.issue.MutableIssue;
import com.atlassian.jira.issue.UpdateIssueRequest;

if (issue.getFixVersions().size() > 0) {
    def componentManager = ComponentManager.getInstance()
    versionManager = componentManager.getVersionManager()
    projectManager = componentManager.getProjectManager()
    issueManager = componentManager.getIssueManager()
    
    def versions = versionManager.getVersions(projectManager.getProjectObjByKey(issue.getProjectObject().getKey())).findAll {it.releaseDate && ! it.released}
    
    def gotit = 0
    def nextVersion = ""
    def nextVersionId = ""
    
    if (versions.size() > 0) {
        versions.each {
            if (gotit == 1){
                nextVersion = it.name
                nextVersionId = it
                gotit = 0
            }
            if (it.name == issue.getFixVersions()[0].getName()) {
                gotit = 1
            }
        }
    }
    
    if (nextVersion != ""){
        def newsummary = sourceIssue.getSummary().replace(issue.getFixVersions()[0].getName(), nextVersion)
        issue.summary = newsummary
        issue.fixVersions = Collections.singleton(nextVersionId)
        def cf = customFieldManager.getCustomFieldObjects(issue).find {it.name == 'Sprint'}
        issue.setCustomFieldValue(cf, null)
    }
}