Register certified "https" protocol for SOAP(Axis 2) request

Question

I created a service to register the "https" protocol and inject the certificate into it using the Socketfactory implementation, but it works well only one request at a time, but when using multi-threading does not work, It’s like you picked up the wrong certificate at the time of the request on the webservice. The webservice SOAP classes were generated by Axis 2 using the WSDL saved from the page.

Code to register protocol and inject certificate (PFX):

public boolean assinar(InputStream pfx, final String password) throws Exception {
    try {
        InputStream in = new ByteArrayInputStream(getBytesFromInputStream(pfx));
        KeyStore ks = KeyStore.getInstance("PKCS12");
        ks.load(in, password.toCharArray());
        in.close();
        Enumeration<String> aliases = ks.aliases();
        String alias = null;

        while (aliases.hasMoreElements()) {
            alias = (String) aliases.nextElement();
            if (ks.isKeyEntry(alias)) break;
        }

        X509Certificate certificate = (X509Certificate) ks.getCertificate(alias);
        PrivateKey privateKey = (PrivateKey) ks.getKey(alias, password.toCharArray());
        SocketFactoryDynamic socketFactoryDinamico = new SocketFactoryDynamic(certificate, privateKey);
        socketFactoryDinamico.setFileCacerts("NFeCacerts");
        Protocol.registerProtocol("https", new Protocol("https", socketFactoryDinamico, 443));
        return true;
    } catch (IOException | NoSuchAlgorithmException | CertificateException | KeyStoreException | UnrecoverableKeyException e) {
        throw e;
    }
}

I want to consult several clients at the same time on the webservice, but the certificates are different. In case you want to know, the webservices are from NF-e Brazil.