### Question:
X509AuthenticationProvider implements AuthenticationProvider { @Override public boolean supports(Class<?> authentication) { return X509AuthenticationToken.class.isAssignableFrom(authentication); }  @Override Authentication authenticate(Authentication authentication); @Override boolean supports(Class<?> authentication);  }### Answer:
@Test void x509AuthenticationIsSupported() { assertTrue(x509AuthenticationProvider.supports(X509AuthenticationToken.class)); }