public AuthenticationProvider getAuthenticationProvider() {
        return authProvider;
    }
Returns the AuthenticationProvider that caused the failure, if any. If
there is no specific AuthenticationProvider involved in this failure,
including if the failure is due to multiple AuthenticationProviders,
this will be null.

@return
    The AuthenticationProvider that caused the failure, or null if there
    is no such specific AuthenticationProvider involved in this failure.
guacamole/src/main/java/org/apache/guacamole/rest/auth/GuacamoleAuthenticationProcessException.java