Get the Request Type Name in an Issue Event Listener or Workflow Function

import com.atlassian.jira.component.ComponentAccessor
import com.atlassian.servicedesk.api.requesttype.RequestTypeService
import com.onresolve.scriptrunner.runner.customisers.PluginModule
import com.onresolve.scriptrunner.runner.customisers.WithPlugin
import com.atlassian.servicedesk.internal.customfields.origin.VpOrigin
import com.atlassian.servicedesk.internal.feature.customer.request.requesttype.CachedImmutableRequestTypeImpl

@WithPlugin("com.atlassian.servicedesk")

@PluginModule
RequestTypeService requestTypeService

def issue = event.issue
def currentUser = ComponentAccessor.jiraAuthenticationContext.loggedInUser
def customFieldManager = ComponentAccessor.customFieldManager

def requestTypeCustomField = customFieldManager.getCustomFieldObjects(issue).findByName('Customer Request Type')
def requestTypeKey = (issue.getCustomFieldValue(requestTypeCustomField) as VpOrigin)?.requestTypeKey

if (!requestTypeKey) {
    return
}

def query = requestTypeService.newQueryBuilder().issue(issue.id).build()
def requestType = requestTypeService.getRequestTypes(currentUser, query).results.find {
    (it as CachedImmutableRequestTypeImpl).key == requestTypeKey
}

def requestTypeName = requestType.name // requestTypeName contains the name of the request type
requestTypeName