小编Mr.*_*iik的帖子

在以前的 Spring Boot 版本（2.1.9）上一切正常。我已将其更新为2.2.2.RELEASE（使用依赖管理插件），并开始出现错误：

org.springframework.dao.DataIntegrityViolationException:
Cannot create index for '' in collection 'testDTO' with keys 'Document{{_id=1, version=1}}' and
options 'Document{{name=optimistic_concurrency_idx}}'.;
nested exception is com.mongodb.MongoCommandException:
Command failed with error 67 (CannotCreateIndex): 'Unknown index plugin '1'' on server mongo:27017.
The full response is { "ok" : 0.0, "errmsg" : "Unknown index plugin '1'", "code" : 67, "codeName" : "CannotCreateIndex" }

我进行了搜索，但没有找到任何方法来修复它。除此之外，我在日志中还有消息：

Registering converter from class java.time.LocalDateTime to class java.time.Instant as reading converter although it doesn't convert from a store-supported type! …

我有一张地图.

Map<UUID, List<UUID>> parentsMap

当我试图清除值时:

parentsMap.values().clear()

它彻底清除了我的地图.我只能这样做:

parentsMap.forEach((k, v) -> v.clear())

我知道当我们编辑地图的.keySet()时,我们会更改原始地图.但是为什么当我们编辑值()时它对键有影响？

我有一个 Maven 项目。pom.xml：

<?xml version="1.0" encoding="UTF-8"?>\n<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"\n         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">\n    <modelVersion>4.0.0</modelVersion>\n\n    <groupId>root</groupId>\n    <artifactId>CourseWork5</artifactId>\n    <version>0.0.1-SNAPSHOT</version>\n    <packaging>jar</packaging>\n\n    <name>coursework</name>\n    <description></description>\n\n    <parent>\n        <groupId>org.springframework.boot</groupId>\n        <artifactId>spring-boot-starter-parent</artifactId>\n        <version>1.4.0.RELEASE</version>\n        <relativePath/> <!-- lookup parent from repository -->\n    </parent>\n\n    <properties>\n        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>\n        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>\n        <java.version>1.8</java.version>\n    </properties>\n\n    <dependencies>\n        <dependency>\n            <groupId>org.springframework.boot</groupId>\n            <artifactId>spring-boot-starter-data-jpa</artifactId>\n        </dependency>\n        <dependency>\n            <groupId>org.springframework.boot</groupId>\n            <artifactId>spring-boot-starter-security</artifactId>\n        </dependency>\n        <dependency>\n            <groupId>org.springframework.boot</groupId>\n            <artifactId>spring-boot-starter-web</artifactId>\n        </dependency>\n        <dependency>\n            <groupId>org.springframework.boot</groupId>\n            <artifactId>spring-boot-starter-thymeleaf</artifactId>\n        </dependency>\n        <dependency>\n            <groupId>mysql</groupId>\n            <artifactId>mysql-connector-java</artifactId>\n            <scope>runtime</scope>\n        </dependency>\n        <dependency>\n            <groupId>org.springframework.boot</groupId>\n            <artifactId>spring-boot-starter-test</artifactId>\n            <scope>test</scope>\n        </dependency>\n        <dependency>\n            <groupId>org.springframework.boot</groupId>\n            <artifactId>spring-boot-devtools</artifactId>\n        </dependency>\n\n        <dependency>\n            <groupId>org.springframework.security</groupId>\n            <artifactId>spring-security-config</artifactId>\n        </dependency>\n        <dependency>\n            <groupId>org.thymeleaf.extras</groupId>\n            <artifactId>thymeleaf-extras-springsecurity4</artifactId>\n        </dependency>\n        <dependency>\n            <groupId>commons-io</groupId>\n            <artifactId>commons-io</artifactId>\n            <version>2.2</version>\n …