Get this "RSA/ECB/OAEPWithSHA-256AndMGF1Padding" combination for ruby

I have this java code for encryption and decryption, which I want to change/convert to Ruby code. I looked up in OpenSSL gem but dint find the "RSA/ECB/OAEPWithSHA-256AndMGF1Padding" combination available for ruby. How do I implement it?

public class EncryptDecryptService {
    
    public String encryptRequestObject(RequestObject requestObject) throws UnsupportedEncodingException, FileNotFoundException, CertificateException, InvalidKeyException, NoSuchAlgorithmException, NoSuchPaddingException, IllegalBlockSizeException, BadPaddingException {
        PublicKey publicKey = getPublicKey(requestObject.getKeyFilename());
        byte[] message = requestObject.getString().getBytes("UTF-8");
        byte[] secret = encrypt(publicKey, message);
        return Base64.encodeBase64String(secret);
    }
    
    public String decryptRequestObject(RequestObject requestObject) throws UnrecoverableKeyException, KeyStoreException, NoSuchAlgorithmException, CertificateException, IOException, InvalidKeyException, NoSuchPaddingException, IllegalBlockSizeException, BadPaddingException {
        PrivateKey privateKey = getPrivateKey(requestObject.getKeyFilename(), requestObject.getKeyPassword());
        byte[] cipherText = Base64.decodeBase64(requestObject.getString());
        byte[] decrypted = decrypt(privateKey, cipherText);
        return new String(decrypted, "UTF-8");
    }
    
    private PublicKey getPublicKey(String filename) throws FileNotFoundException, CertificateException {
        FileInputStream fin = new FileInputStream(filename);
        CertificateFactory factory = CertificateFactory.getInstance("X.509");
        X509Certificate certificate = (X509Certificate) factory.generateCertificate(fin);
        PublicKey publicKey = certificate.getPublicKey();
        return publicKey;
    }
    
    private PrivateKey getPrivateKey(String filename, String password) throws KeyStoreException, NoSuchAlgorithmException, CertificateException, IOException, UnrecoverableKeyException {
        FileInputStream fin = new FileInputStream(filename);
        KeyStore ks = KeyStore.getInstance("pkcs12");
        ks.load(fin, password.toCharArray());
        String str = ks.aliases().nextElement();
        PrivateKey privateKey = (PrivateKey) ks.getKey(str, password.toCharArray());
        return privateKey;
    }
    
    private byte[] encrypt(PublicKey key, byte[] plainText) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
        Cipher cipher = Cipher.getInstance("RSA/ECB/OAEPWithSHA-256AndMGF1Padding");
        cipher.init(Cipher.ENCRYPT_MODE, key);
        return cipher.doFinal(plainText);
    }
    
    private byte[] decrypt(PrivateKey key, byte[] cipherText) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
        Cipher cipher = Cipher.getInstance("RSA/ECB/OAEPWithSHA-256AndMGF1Padding");
        cipher.init(Cipher.DECRYPT_MODE, key);
        return cipher.doFinal(cipherText);
    }
}