You can copy and paste the method `void uploadAllNugetToArtifactory()` into your Jenkinsfile and use it in your `script { ... }`.

uploadAllNugetToArtifactory.groovy

def call(Map params = [:]) {
    uploadAllNugetToArtifactory(params)
}

void uploadAllNugetToArtifactory(Map params = [:]) {
    pipelineHelper(sharedLibrary: this, parameters: params) {

        params.nugetPackOutputDir = params.get('nugetPackOutputDir', 'nuget-pack-out')
        params.nugetReleases = params.get('nugetReleases', 'nuget-releases')
        params.nugetFeatures = params.get('nugetFeatures', 'nuget-features')
        params.uploadFirstPackage = params.get('uploadFirstPackage', false )

        // check gitversion access
        if (env.GitVersion_SemVer == '') {
            throw new Exception("dotnet tool GitVersion is required.")
        }

        def preRelease = env.GitVersion_PreReleaseLabel && !(env.BRANCH_NAME ==~ /(?i)(master|releases?\/.+)/)

        def nugetRepository = preRelease ? params.nugetFeatures : params.nugetReleases
        def filesToUploadPattern = "**/${params.nugetPackOutputDir}/*.nupkg"

        // find files to upload
        def findFilesToUpload = findFiles(glob: filesToUploadPattern)
        if (findFilesToUpload.length == 0) {
            throw new Exception("No packages were found using the pattern ${filesToUploadPattern}")
        }

        // check if all release package already exists
        if (!preRelease) {
            def artifactoryURL = infra.getArtifactoryUrl()
            def spec = new UploadSpec()

            //  Reduce list to the 1st file
            if (params.uploadFirstPackage) {
                while(findFilesToUpload.length() > 1) { findFilesToUpload.removeLast() }
            }

            // Test that we can even find any packages to upload, otherwise fail build
            boolean skipPublish = false

            findFilesToUpload.each { file ->
                def head = new URL("${artifactoryURL}/threeshape-nuget/${file.name}").openConnection()
                head.setRequestMethod("HEAD")
                def alreadyPublished = head.getResponseCode().equals(200)
                skipPublish |= alreadyPublished
                if (alreadyPublished) {
                    echo "Upload of ${file.name} nuget to [${nugetRepository}] skipped as it already exists."
                }
                spec.addSpec(
                    pattern: "${file}",
                    target: "${nugetRepository}/"
                )
            }

            if (skipPublish) {
                echo "Upload of nuget from [${env.JOB_NAME}@${env.BRANCH_NAME}], publishing to [${nugetRepository}] skipped as it already exists."
            } else {
                uploadToArtifactory(repository : nugetRepository, uploadSpec : spec)
            }
        }
    }
}