public void setRegexpPattern(final String regexpPattern) {
        CommonHelper.assertNotNull("regexpPattern", regexpPattern);
        this.regexpPattern = regexpPattern;
        this.pattern = Pattern.compile(regexpPattern);
    }
<p>Setter for the field <code>regexpPattern</code>.</p>

@param regexpPattern a {@link String} object
pac4j-http/src/main/java/org/pac4j/http/credentials/authenticator/AbstractRegexpAuthenticator.java