static int validateMaxNumConnections(int maxNumConnections) {
        if (maxNumConnections <= 0) {
            throw new IllegalArgumentException("maxNumConnections: " + maxNumConnections + " (expected: > 0)");
        }
        return maxNumConnections;
    }
Validates the maximum allowed number of open connections. It must be a positive number.
core/src/main/java/com/linecorp/armeria/server/ConnectionLimitingHandler.java