只做了一次 get，为什么 LinkedHashMap 遍历就失败了？

import java.util.ConcurrentModificationException;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

public class Main {
    static void run(String mode) {
        boolean accessOrder = !mode.equals("insertion-get-a");
        LinkedHashMap<String, Integer> map =
                new LinkedHashMap<>(16, 0.75f, accessOrder);
        map.put("A", 10);
        map.put("B", 20);
        map.put("C", 30);
        String before = String.join(",", map.keySet());
        Iterator<Map.Entry<String, Integer>> iterator = map.entrySet().iterator();
        Map.Entry<String, Integer> first = iterator.next();
        String operation;
        if (mode.equals("access-contains-a")) {
            operation = "containsKey(A)=" + map.containsKey("A");
        } else if (mode.equals("access-get-c")) {
            operation = "get(C)=" + map.get("C");
        } else if (mode.equals("access-entry-value")) {
            operation = "entry.getValue()=" + first.getValue();
        } else {
            operation = "get(A)=" + map.get("A");
        }
        String after = String.join(",", map.keySet());
        String next;
        try {
            next = iterator.next().getKey();
        } catch (ConcurrentModificationException e) {
            next = e.getClass().getSimpleName();
        }
        System.out.printf(
                "{\"mode\":\"%s\",\"accessOrder\":%s,\"before\":\"%s\","
                + "\"first\":\"%s\",\"operation\":\"%s\",\"after\":\"%s\","
                + "\"next\":\"%s\",\"size\":%d}%n",
                mode, accessOrder, before, first.getKey(), operation, after, next, map.size());
        List<String> expected = mode.equals("access-get-a")
                ? List.of("B", "C", "A") : List.of("A", "B", "C");
        if (!List.copyOf(map.keySet()).equals(expected)) {
            throw new AssertionError("wrong encounter order");
        }
    }

    public static void main(String[] args) {
        run("insertion-get-a");
        run("access-get-a");
        run("access-contains-a");
        run("access-get-c");
        run("access-entry-value");
    }
}