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 com.cloudbees.jenkins.plugins.sshcredentials.impl.*
import org.jenkinsci.plugins.plaincredentials.*
import org.jenkinsci.plugins.plaincredentials.impl.*
import hudson.util.Secret
import hudson.plugins.sshslaves.*
import org.apache.commons.fileupload.* 
import org.apache.commons.fileupload.disk.*
import java.nio.file.Files

domain = Domain.global()
store = Jenkins.instance.getExtensionList('com.cloudbees.plugins.credentials.SystemCredentialsProvider')[0].getStore()

priveteKey = new BasicSSHUserPrivateKey(
CredentialsScope.GLOBAL,
"jenkins-slave-key",
"root",
new BasicSSHUserPrivateKey.UsersPrivateKeySource(),
"",
""
)

usernameAndPassword = new UsernamePasswordCredentialsImpl(
  CredentialsScope.GLOBAL,
  "jenkins-slave-password", "Jenkis Slave with Password Configuration",
  "root",
  "jenkins"
)

secretText = new StringCredentialsImpl(
CredentialsScope.GLOBAL,
"secret-text",
"Secret Text Description",
Secret.fromString("some secret text goes here"))

factory = new DiskFileItemFactory()
dfi = factory.createItem("", "application/octet-stream", false, "filename")
out = dfi.getOutputStream()
file = new File("/path/to/some/file")
Files.copy(file.toPath(), out)
FileCredentailsImpl can take a file from a do
secretFile = new FileCredentialsImpl(
CredentialsScope.GLOBAL,
"secret-file",
"Secret File Description"
dfi, // Don't use FileItem
"",
"")


store.addCredentials(domain, priveteKey)
store.addCredentials(domain, usernameAndPassword)
store.addCredentials(domain, secretText)
store.addCredentials(domain, secretFile)