为什么由于LinkedHashMap启动中的一些问题而导致Jackson ObjectMapper解析错误?

我想使用ObjectMapper阅读此JSON:

{
  "basePath": "/v1",
  "models": {
    "Course":{
      "number": "integer",
      "name": "string",
      "description": "string"
    },
    "Department": {
      "name": "string",
      "code": "string"
    }
  }
}

ObjectMapper mapper = new ObjectMapper();
InputStream inputStream = Input.class.getResourceAsStream("/input.json");
Input input = mapper.readValue(inputStream, Input.class);

其中输入为:

public class Input {

  String basePath;
  Map<String, Map<String, Map<String, String>>> models;

  public String getBasePath() {
    return basePath;
  }

  public void setBasePath(String basePath) {
    this.basePath = basePath;
  }

  public Map<String, Map<String, Map<String, String>>> getModels() {
    return models;
  }

  public void setModels(Map<String, Map<String, Map<String, String>>> models) {
    this.models = models;
  }
}

但是我得到了JSON映射错误。

Can not instantiate value of type [map type; class java.util.LinkedHashMap, [simple type, class java.lang.String] -> [simple type, class java.lang.String]] from JSON String; no single-String constructor/factory method