return running;
        }

        /**
         * Waits for the crawling thread to terminate.
         * This method blocks until the thread completes its execution.
         * Interrupted exceptions are caught and logged at debug level.
         */
        public void awaitTermination() {
            try {
                join();
            } catch (final InterruptedException e) {

            return null;
        }
        if (list.size() >= 2) {
            String msg = "The size of selected list is over 1: " + list.size();
            throw new FetchingOverSafetySizeException(msg, 1); // immediately caught by caller and translated
        }
        return list.get(0);
    }

    @Override

            return null;
        }
        if (list.size() >= 2) {
            String msg = "The size of selected list is over 1: " + list.size();
            throw new FetchingOverSafetySizeException(msg, 1); // immediately caught by caller and translated
        }
        return list.get(0);
    }

    @Override

            return null;
        }
        if (list.size() >= 2) {
            String msg = "The size of selected list is over 1: " + list.size();
            throw new FetchingOverSafetySizeException(msg, 1); // immediately caught by caller and translated
        }
        return list.get(0);
    }

    @Override

    }

    /**
     * Sets the uncaught exception handler for this IndexUpdater thread.
     *
     * @param eh the uncaught exception handler to set
     */
    @Override
    public void setUncaughtExceptionHandler(final UncaughtExceptionHandler eh) {
        super.setUncaughtExceptionHandler(eh);
    }

    /**
     * Sets the default uncaught exception handler for all threads.
     *