Java: Feign Client mTLS (by enabling custom keystore and truststore for a specific enpoint)

HelloFeignmTLS.java

// How to test
//
// Update uriPrefix, keystoreFile, keystorePassword, truststoreFile, truststorePassword with your values and run:
//   curl -L -O https://repo1.maven.org/maven2/io/github/openfeign/feign-core/11.6/feign-core-11.6.jar
//   java -cp feign-core-11.6.jar HelloFeignmTLS.java

// Feign
import feign.Feign;
import feign.RequestLine;

// Required for mTLS
import feign.Client;
import java.io.FileInputStream;
import java.io.InputStream;
import java.security.KeyStore;
import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLSocketFactory;
import javax.net.ssl.TrustManagerFactory;
import javax.net.ssl.KeyManagerFactory;

public class HelloFeignmTLS {
  private static final String uriPrefix = "https://10.10.10.10.nip.io";  // Server protected by mTLS
  private static final String keystoreFile = "/path/to/client.pkcs12";
  private static final String keystorePassword = "<keystorepass>";
  private static final String truststoreFile = "/path/to/truststore.pkcs12";
  private static final String truststorePassword = "<truststorepass>";

  public static void main(String... args) throws Exception {
    SSLSocketFactory sslSocketFactory = sslSocketFactory(keystoreFile, keystorePassword, truststoreFile, truststorePassword);

    MyClient myClient = Feign.builder()
                             .client(new Client.Default(sslSocketFactory, null))
                             .target(MyClient.class, uriPrefix);

    String response = myClient.getRoot();
    System.out.println(response);
  }

  interface MyClient {
    @RequestLine("GET /")
    String getRoot();
  }

  private static SSLSocketFactory sslSocketFactory(
      String keystoreFile,
      String keystorePassword,
      String truststoreFile,
      String truststorePassword)
      throws Exception {

    // Keystore
    KeyStore keystore = KeyStore.getInstance(KeyStore.getDefaultType());
    try (InputStream in = new FileInputStream(keystoreFile)) {
      keystore.load(in, keystorePassword.toCharArray());
    }
    KeyManagerFactory keyManagerFactory =
        KeyManagerFactory.getInstance(KeyManagerFactory.getDefaultAlgorithm());
    keyManagerFactory.init(keystore, keystorePassword.toCharArray());

    // Truststore
    KeyStore truststore = KeyStore.getInstance(KeyStore.getDefaultType());
    try (InputStream in = new FileInputStream(truststoreFile)) {
      truststore.load(in, truststorePassword.toCharArray());
    }
    TrustManagerFactory trustManagerFactory =
        TrustManagerFactory.getInstance(TrustManagerFactory.getDefaultAlgorithm());
    trustManagerFactory.init(truststore);

    // SSLContext
    SSLContext sslContext = SSLContext.getInstance("TLS");
    sslContext.init(
        keyManagerFactory.getKeyManagers(),
        trustManagerFactory.getTrustManagers(),
        null);

    return sslContext.getSocketFactory();
  }
}