title: spring security AuthenticationManager vs AuthenticationProvider?
body: <p>Can someone tell me the difference between an <code>AuthenticationManager</code> and an <code>AuthenticationProvider</code> in Spring Security?</p>
  
  <p>How are they used and how are they called. It is my understanding that a <code>SecurityFilter</code> will call the <code>AuthenticationManager</code> to authenticate an <code>Authentication</code> object? But then where does the <code>AuthenticationProvider</code> come into play?</p>
  
  <p>Thanks!</p>