将ConfigurationProperties与内部类一起使用会导致“属性未绑定”异常

我有一个 @ConfigurationProperties -注释 @Configuration -类调用 库配置 。它使用内部类作为属性/配置结构的类型定义。当类是内部类而不是独立类时,我会得到 “元素[…]未被绑定” 错误/异常。为什么会这样,我该怎么解决?

application.yml

initdata:
  library:
    name: awesome library
    books:
      - title: Book1
        author: Author Abc
      - title: Book2
        author: Author Xyz

库配置.java

import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Configuration;

@Configuration
@ConfigurationProperties(prefix = "initdata.library")
public class LibraryConfiguration {
    private String name;
    private List<Book> books;

    // getters left out for simplicity of example
    public void setName(String name) {
        this.name = name;
    }
    public void setBooks(List<Book> books) {
        this.books = books;
    }

    public LibraryConfiguration() {
    }

    public static class Book {
        private String title;
        private String author;

        public Book() {
        }
        // getters left out for simplicity of example
        public void setTitle(String title) {
            this.title = title;
        }
        public void setAuthor(String author) {
            this.author = author;
        }
    }
}