Map to Json，Json to Map？我使用Gson库。是不存在问题的
Map到JSON字符串

Gson gson = new GsonBuilder().setPrettyPrinting().create();
Map<String, String> map = new HashMap<String, String>();
map.put("111", "AAAAA");
map.put("222", "BBBBB");
String mapString = gson.toJson(map);
System.out.println(mapString);

输出

{
  "222": "BBBBB",
  "111": "AAAAA"
}

JSON String to Map

Gson gson = new GsonBuilder().setPrettyPrinting().create();
String mapString  = "{\"222\": \"BBBBB\",\"111\": \"AAAAA\"}";
Map<String, String> map = gson.fromJson(mapString, Map.class);
System.out.println(map.get("111"));

输出

AAAAA

我不建议你用你现在的方式做这件事。我创建了一个示例项目，展示了如何使用Map<String，Object>而不是Map<String，String>来实现。
https://github.com/djangofan/json-serialization-jackson-example/blob/main/src/test/java/com/example/TestObjectsTest.java
在该示例中：

....
  private static final ObjectMapper MAPPER = new ObjectMapper();
  .....
  @Test
  void testDeserialization() {
    Map<String, Object> linkedHashMap = new LinkedHashMap<>();
    linkedHashMap.put("foo", "bar");
    linkedHashMap.put("bar", "foo");

    TestObjects.Bar bar = TestObjects.Bar.builder()
        .id(3)
        .description("bar description")
        .stringBoolean("false")
        .nestedMap(linkedHashMap)
        .build();
    TestObjects.Foo foo = TestObjects.Foo.builder()
        .id(1)
        .description("foo description")
        .primitiveBoolean(false)
        .bar(bar)
        .build();

    String serialized = null;
    try {
      serialized = MAPPER.writeValueAsString(foo);
    } catch (JsonProcessingException e) {
      throw new RuntimeException(e);
    }

    assertTrue(serialized.contains("foo description"));
    try {
      TestObjects.Foo foo1 = MAPPER.readValue(serialized, TestObjects.Foo.class);
      TestObjects.Bar bar1 = foo1.getBar();

      assertEquals(bar1.id, 3);
    } catch (JsonProcessingException e) {
      throw new RuntimeException(e);
    }

  }