jenkins-install-global-shared-library.groovy

import jenkins.model.Jenkins
import jenkins.plugins.git.GitSCMSource
import jenkins.plugins.git.traits.BranchDiscoveryTrait
import org.jenkinsci.plugins.workflow.libs.GlobalLibraries
import org.jenkinsci.plugins.workflow.libs.LibraryConfiguration
import org.jenkinsci.plugins.workflow.libs.SCMSourceRetriever

def sharedLibraryName = "mySharedLibName"
def repository = "git@github.com:[OWNER]/[REPO].git"

if (! Jenkins.instance.getDescriptor(GlobalLibraries).getLibraries().findAll{ it.getName() == sharedLibraryName }) {
    def libraries = Jenkins.instance.getDescriptor(GlobalLibraries).getLibraries()
    def scm = new GitSCMSource(repository)
    scm.traits = [new BranchDiscoveryTrait()]
    def library = new LibraryConfiguration(sharedLibraryName, new SCMSourceRetriever(scm))    
    library.defaultVersion = "master"
    library.implicit = true
    library.allowVersionOverride = true
    library.includeInChangesets = false
    libraries << library
    def gSettings = Jenkins.instance.getExtensionList(GlobalLibraries.class)[0]
    gSettings.libraries = libraries
    gSettings.save()
    println 'Global Shared Libraries configured succefully'
}

Thank you so much Marcos