public static void verifyGroupId(final String groupId) {
        if (StringUtils.isBlank(groupId)) {
            throw new IllegalArgumentException("Blank groupId");
        }
        if (!GROUP_ID_PATTER.matcher(groupId).matches()) {
            throw new IllegalArgumentException(
                "Invalid group id, it should be started with character 'a'-'z' or 'A'-'Z',"
                        + " and followed with numbers, english alphabet, '-' or '_'. ");
        }
    }
Global thread pool to run closure.
jraft-core/src/main/java/com/alipay/sofa/jraft/util/Utils.java