public class I18nContainerRequestFilter implements ContainerRequestFilter {
private Locale determineLocaleFromQueryParameter(MultivaluedMap<String, String> queryParameters) {
    ...
    if (!isValidLanguageTag(localeString)) {
        throw new BadRequestException(String.format("Language parameter: %s is not allowed", localeString));
    }
    ...
}
} 

class PreMatchContainerRequestContext ...{
public synchronized BuiltResponse filter() {
    RESTEasyTracingLogger tracingLogger = RESTEasyTracingLogger.getInstance(this.httpRequest);
    long totalTimestamp = tracingLogger.timestamp("REQUEST_FILTER_SUMMARY");    while(this.requestFilters != null && this.currentFilter < this.requestFilters.length) {
        ContainerRequestFilter filter = this.requestFilters[this.currentFilter++];        try {
            this.suspended = false;
            this.response = null;
            this.throwable = null;
            this.inFilter = true;
            long timestamp = tracingLogger.timestamp("REQUEST_FILTER");
            filter.filter(this);
            tracingLogger.logDuration("REQUEST_FILTER", timestamp, new Object[]{filter});
        } catch (IOException var10) {
            throw new ApplicationException(var10);
        } finally {
            this.inFilter = false;
        }
...
}