*
     * @param userAgent The user agent string to look up in the directives
     * @return The Directive object matching the user agent, or null if no matching directive is found or if userAgent is null
     */
    public Directive getDirective(final String userAgent) {
        if (userAgent == null) {
            return null;
        }

        this.authSchemeProviderMap = authSchemeProviderMap;
    }

    /**
     * Sets the user agent string.
     * @param userAgent The user agent string.
     */
    public void setUserAgent(final String userAgent) {
        this.userAgent = userAgent;
    }

    /**
     * Sets the credentials provider.
     * @param credentialsProvider The credentials provider.
     */