HTML表单提交不适用于Spring Boot 2.3.1

从Spring Boot 2.2.7切换到Spring Boot 2.3.1后，针对我的具体情况，在提交表单时进行实体转换不再起作用

Entity conversion upon form submit for my specific case is not working anymore after switching from Spring Boot 2.2.7 to Spring Boot 2.3.1

Category.java

Category.java

@Entity @Getter @Setter
public class Category implements Serializable {
    private Integer id;
    private String name;
}

SearchForm.java:

SearchForm.java:

@Getter @Setter
public class SearchForm implements Serializable {
    private String q;
    private Category c;
}

HTML表单:

<form method="get" th:action="@{/}" th:object="${searchForm}">
    <input th:field="*{q}" type="text" />
    <select th:field="*{c}">
        <option th:each="cat : ${categories}" th:value="${cat.id}"  th:text="${cat.name}" />
    </select>
</form>

Controller.java:

Controller.java:

@PostMapping
public String post( @ModelAttribute final SearchForm searchForm ) {
    // ...
}

以前，在Spring Boot 2.2.7中，表单commit会将"c"转换为"c".从HTML表单(选择保留类别的ID)到SearchForm.java中的类别实体

Previously with Spring Boot 2.2.7 form submit would convert "c" from HTML form (select is holding ID of Category) to Category entity in SearchForm.java

切换到Spring Boot 2.3.1之后，它不再起作用.而是在日志中显示错误:

After switching to Spring Boot 2.3.1 this is not working anymore. An error is displayed in log instead:

字段"c"上的对象"searchForm"中的字段错误:拒绝的值[424]；代码[typeMismatch.searchForm.c，typeMismatch.c，typeMismatch.com.thevegcat.app.category.Category，typeMismatch]；参数[org.springframework.context.support.DefaultMessageSourceResolvable:代码[searchForm.c，c];参数[];默认消息[c]]；默认消息[未能将类型'java.lang.String'的属性值转换为属性'c'的必需类型'com.thevegcat.app.category.Category'；嵌套的异常为java.lang.IllegalStateException:无法将属性"c"的类型"java.lang.String"的值转换为所需的类型"com.thevegcat.app.category.Category":未找到匹配的编辑器或转换策略]]

Field error in object 'searchForm' on field 'c': rejected value [424]; codes [typeMismatch.searchForm.c,typeMismatch.c,typeMismatch.com.thevegcat.app.category.Category,typeMismatch]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [searchForm.c,c]; arguments []; default message [c]]; default message [Failed to convert property value of type 'java.lang.String' to required type 'com.thevegcat.app.category.Category' for property 'c'; nested exception is java.lang.IllegalStateException: Cannot convert value of type 'java.lang.String' to required type 'com.thevegcat.app.category.Category' for property 'c': no matching editors or conversion strategy found]]