protected String buildAuthenticationRequestUrl(final Map<String, String> params) {
        // Build authentication request query string
        String queryString;
        try {
            val parameters = params.entrySet().stream().collect(
                Collectors.toMap(Map.Entry::getKey, e -> Collections.singletonList(e.getValue())));
            queryString = AuthenticationRequest.parse(parameters).toQueryString();
            queryString = queryString.replaceAll("\\+", "%20");
        } catch (final Exception e) {
            throw new OidcException(e);
        }
        return client.getConfiguration().getOpMetadataResolver().load().getAuthorizationEndpointURI().toString() + '?' + queryString;
    }
<p>buildParams.</p>

@param webContext a {@link WebContext} object
@return a {@link Map} object
pac4j-oidc/src/main/java/org/pac4j/oidc/redirect/OidcRedirectionActionBuilder.java