Jenkins Credential Binding Plugin: creating a secret file programmatically

create-secret-file.groovy

import jenkins.model.*
import com.cloudbees.plugins.credentials.*
import com.cloudbees.plugins.credentials.common.*
import com.cloudbees.plugins.credentials.domains.*
import com.cloudbees.plugins.credentials.impl.*
import org.jenkinsci.plugins.plaincredentials.*
import org.jenkinsci.plugins.plaincredentials.impl.*
import org.apache.commons.fileupload.FileItem

//Replace file-id, file-description, filepath and filename with appropriate values for your file
final File file = new File('filepath/filename')
fileItem = [ getName: { return "filename" },  get: { return file.getBytes() } ] as FileItem
secretFile = new FileCredentialsImpl(
   CredentialsScope.GLOBAL,
   "file-id",
   "file-description",
   fileItem, // Don't use FileItem
   null,
   null)
store.addCredentials(domain, secretFile)