title: How can I configure Spring Security to use custom AuthenticationManager implementation?
body: <p>What I have is:</p>
  
  <pre><code>&lt;authentication-manager alias="authenticationManager"&gt;
      &lt;authentication-provider user-service-ref="securityService"/&gt;
  &lt;/authentication-manager&gt;
  </code></pre>
  
  <p>As I understand, the default AuthenticationManager implementation is used. I need to override its method <code>authenticate</code>. Is there a way to provide my own AuthenticationManager implementation?</p>