http://www.bouncycastle.org/java.html: The Bouncy Castle Crypto package is a Java implementation of cryptographic algorithms. This jar contains JCE provider and lightweight API for the Bouncy Castle Cryptography APIs for JDK 1.5 to JDK 1.8.
  • The Legion of the Bouncy Castle Inc. 
package org.bouncycastle.crypto.tls;

public abstract class ServerOnlyTlsAuthentication
    implements TlsAuthentication
{
    public final TlsCredentials getClientCredentials(CertificateRequest certificateRequest)
    {
        return null;
    }
}