Spring boot Spring Boot Maven插件错误-运行时发生异常。null:NullPointerException

运行项目时，我收到以下错误消息

[ERROR]无法执行目标org.springframework.boot:spring boot maven plugin:2.0.2.RELEASE:run（默认cli）on project KotlinJwt:运行时发生异常。null:NullPointerException->[Help 1]

日志

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.example</groupId>
    <artifactId>KotlinJwt</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>KotlinJwt</name>
    <description>Spring Boot Kotlin REST API Example</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.2.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
        <kotlin.version>1.2.41</kotlin.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-webflux</artifactId>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.module</groupId>
            <artifactId>jackson-module-kotlin</artifactId>
        </dependency>
        <dependency>
            <groupId>org.jetbrains.kotlin</groupId>
            <artifactId>kotlin-stdlib-jdk8</artifactId>
        </dependency>
        <dependency>
            <groupId>org.jetbrains.kotlin</groupId>
            <artifactId>kotlin-reflect</artifactId>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>io.projectreactor</groupId>
            <artifactId>reactor-test</artifactId>
            <scope>test</scope>
        </dependency>

            <dependency>
            <groupId>io.springfox</groupId>
            <artifactId>springfox-swagger2</artifactId>
            <version>2.8.0</version>
        </dependency>
        <dependency>
            <groupId>io.springfox</groupId>
            <artifactId>springfox-swagger-ui</artifactId>
            <version>2.8.0</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-security</artifactId>
        </dependency>
        <dependency>
            <groupId>io.jsonwebtoken</groupId>
            <artifactId>jjwt</artifactId>
            <version>0.9.0</version>
        </dependency>

    </dependencies>

    <build>
        <sourceDirectory>${project.basedir}/src/main/kotlin</sourceDirectory>
        <testSourceDirectory>${project.basedir}/src/test/kotlin</testSourceDirectory>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <mainClass>com.example.demo.KotlinJwtApplication</mainClass>
                </configuration>
            </plugin>
            <plugin>
                <artifactId>kotlin-maven-plugin</artifactId>
                <groupId>org.jetbrains.kotlin</groupId>
                <configuration>
                    <args>
                        <arg>-Xjsr305=strict</arg>
                    </args>
                    <compilerPlugins>
                        <plugin>spring</plugin>
                    </compilerPlugins>
                </configuration>
                <dependencies>
                    <dependency>
                        <groupId>org.jetbrains.kotlin</groupId>
                        <artifactId>kotlin-maven-allopen</artifactId>
                        <version>${kotlin.version}</version>
                    </dependency>
                    <dependency>
                        <groupId>org.jetbrains.kotlin</groupId>
                        <artifactId>kotlin-maven-noarg</artifactId>
                        <version>${kotlin.version}</version>
                    </dependency>
                </dependencies>
            </plugin>
        </plugins>
    </build>
</project>

4.0.0
com.example
. 起初，SpringBootMaven插件中似乎并没有mainClass标记，但并没有抛出mainClassfound错误
其他代码：
对于Kotlin，主类应该是顶级函数，因此替换

@SpringBootApplication
class KotlinJwtApplication {
    @Bean
    fun bCryptPasswordEncoder() : BCryptPasswordEncoder {
        return BCryptPasswordEncoder()
    }

    fun main(args: Array<String>) {
        runApplication<KotlinJwtApplication>(*args)
    }
}

@springboot应用程序
类kotlinjwt应用程序{
@豆子
有趣的bCryptPasswordEncoder（）：bCryptPasswordEncoder{
返回BCryptPasswordEncoder（）
}
趣味主线（args:Array）{
运行应用程序（*args）
}
}

与

@springboot应用程序
类kotlinjwt应用程序{
@豆子
有趣的bCryptPasswordEncoder（）：bCryptPasswordEncoder{
返回BCryptPasswordEncoder（）
}
}
趣味主线（args:Array）{
运行应用程序（*args）
}

然后，您还可以删除

<configuration>
    <mainClass>com.example.demo.KotlinJwtApplication</mainClass>
</configuration>


com.example.demo.KotlinJwtApplication

从您
pom.xml

@SpringBootApplication
class KotlinJwtApplication {
    @Bean
    fun bCryptPasswordEncoder() : BCryptPasswordEncoder {
        return BCryptPasswordEncoder()
    }

    fun main(args: Array<String>) {
        runApplication<KotlinJwtApplication>(*args)
    }
}

@SpringBootApplication
class KotlinJwtApplication {
    @Bean
    fun bCryptPasswordEncoder() : BCryptPasswordEncoder {
        return BCryptPasswordEncoder()
    }
}

fun main(args: Array<String>) {
    runApplication<KotlinJwtApplication>(*args)
}

<configuration>
    <mainClass>com.example.demo.KotlinJwtApplication</mainClass>
</configuration>