return getProperties().remove(key);
    }

    @Override
    public void save(final OutputStream out, final String comments) {
        throw new UnsupportedOperationException("Unsupported operation.");
    }

    @Override
    public Object setProperty(final String key, final String value) {
        return getProperties().setProperty(key, value);
    }

    @Override
    public int size() {

            return;
        }

        if (!ComponentUtil.getFessConfig().isWebApiPopularWord()) {
            writeJsonResponse(HttpServletResponse.SC_BAD_REQUEST, escapeJsonKeyValue(MESSAGE_FIELD, "Unsupported operation."));
            return;
        }

        final String seed = request.getParameter("seed");
        String[] tags = SearchRequestParams.getParamValueArray(request, "label");