private AuthenticationProvider getAuthenticationProvider(String identifier) {

        // Iterate through all installed AuthenticationProviders, searching for
        // the given identifier
        for (AuthenticationProvider authProvider : authProviders) {
            if (authProvider.getIdentifier().equals(identifier))
                return authProvider;
        }

        // No such AuthenticationProvider found
        return null;

    }
Returns the AuthenticationProvider having the given identifier. If no
such AuthenticationProvider has been loaded, null is returned.

@param identifier
    The identifier of the AuthenticationProvider to locate.

@return
    The AuthenticationProvider having the given identifier, or null if
    no such AuthenticationProvider is loaded.
guacamole/src/main/java/org/apache/guacamole/rest/extension/ExtensionRESTService.java