@Override
    public boolean supports(final Credential credential) {
        return credential instanceof PrincipalBearingCredential;
    }
AuthenticationHandler which authenticates Principal-bearing credentials.
Authentication must have occurred at the time the Principal-bearing
credentials were created, so we perform no further authentication. Thus
merely by being presented a PrincipalBearingCredential, this handler returns
true.

@author Andrew Petro
@since 3.0.0
support/cas-server-support-trusted/src/main/java/org/apereo/cas/adaptors/trusted/authentication/handler/support/PrincipalBearingCredentialsAuthenticationHandler.java