如何使用 Gradle 将快照工件部署到 Maven 存储库并生成有效的 maven-metadata.xml？

Question

我有以下build.gradle脚本：

apply plugin: 'java'
apply plugin: 'maven'

compileJava {
    targetCompatibility = "1.8"
    sourceCompatibility = "1.8"
    options.encoding = 'UTF-8'
}

ext.username = System.getProperty('username') != null ? System.getProperty('username') : mavenUser
ext.password = System.getProperty('password') != null ? System.getProperty('password') : mavenPassword

description = "Example project that shows how to use Gradle to build and deploy artifacts to Nexus"

configurations {
    deployerJars
}

repositories {
    maven { url "http://nexus:8081/nexus/content/groups/my-group/" }
    mavenCentral()
}

dependencies {
    deployerJars "org.apache.maven.wagon:wagon-http:2.2"
    testCompile group: 'junit', name: 'junit', version: '4.11'
}

// Gradle build Configuration to publish artifacts to maven artifact manager
uploadArchives {
    repositories.mavenDeployer {
            configuration = configurations.deployerJars
            repository(url: "http://nexus:8081/nexus/content/repositories/my-snapshots/") {
                authentication(userName: username, password: password)
            }
            pom.groupId = "com.foo.bar"
            pom.artifactId = "my-gradle-app"
            pom.version = "1.0-SNAPSHOT"
    }
}

// ------------------------------------------------------
// EXAMPLE: custom tasks for creating source/javadoc jars
task sourcesJar(type: Jar, dependsOn: classes) {
    classifier = 'sources'
    from sourceSets.main.allSource
}

task javadocJar(type: Jar, dependsOn: javadoc) {
    classifier = 'javadoc'
    from javadoc.destinationDir
}

// add javadoc/source jar tasks as artifacts
artifacts {
    archives sourcesJar
    archives javadocJar
}

当我执行以下命令时，构建和部署成功：

$ gradle clean upload -Dusername=myUsername -Dpassword=myPassword

生成的maven-metadata.xml文件如下所示：

<metadata>
    <groupId>com.foo.bar</groupId>
    <artifactId>my-gradle-app</artifactId>
    <version>1.0-SNAPSHOT</version>
    <versioning>
        <snapshot>
            <timestamp>20170906.143113</timestamp>
            <buildNumber>1</buildNumber>
        </snapshot>
        <lastUpdated>20170906143113</lastUpdated>
    </versioning>
</metadata>

这些是实际部署到 Nexus 的文件：

my-gradle-app-1.0-20170906.143113-1-javadoc.jar
my-gradle-app-1.0-20170906.143113-1-javadoc.jar.md5
my-gradle-app-1.0-20170906.143113-1-javadoc.jar.sha1
my-gradle-app-1.0-20170906.143113-1-sources.jar
my-gradle-app-1.0-20170906.143113-1-sources.jar.md5
my-gradle-app-1.0-20170906.143113-1-sources.jar.sha1
my-gradle-app-1.0-20170906.143113-1.jar
my-gradle-app-1.0-20170906.143113-1.jar.md5
my-gradle-app-1.0-20170906.143113-1.jar.sha1
my-gradle-app-1.0-20170906.143113-1.pom
my-gradle-app-1.0-20170906.143113-1.pom.md5
my-gradle-app-1.0-20170906.143113-1.pom.sha1

来自 Maven 背景，我希望在maven-metadata.xml文件中看到以下内容：

<metadata>
    <groupId>com.foo.bar</groupId>
    <artifactId>my-gradle-app</artifactId>
    <version>1.0-SNAPSHOT</version>
    <versioning>
        <snapshot>
            <timestamp>20170906.143113</timestamp>
            <buildNumber>1</buildNumber>
        </snapshot>
        <lastUpdated>20170906143113</lastUpdated>
    </versioning>
    <snapshotVersions>
        <snapshotVersion>
            <classifier>javadoc</classifier>
            <extension>jar</extension>
            <value>1.0-20170906.143113-1</value>
            <updated>20170906140847</updated>
        </snapshotVersion>
        <snapshotVersion>
            <classifier>sources</classifier>
            <extension>jar</extension>
            <value>1.0-20170906.143113-1</value>
            <updated>20170906140847</updated>
        </snapshotVersion>
        <snapshotVersion>
            <extension>jar</extension>
            <value>1.0-20170906.143113-1</value>
            <updated>20170906140844</updated>
        </snapshotVersion>
        <snapshotVersion>
            <extension>pom</extension>
            <value>1.0-20170906.143113-1</value>
            <updated>20170906140847</updated>
        </snapshotVersion>
    </snapshotVersions>
</metadata>

如果我重新运行部署，我会期望maven-metadata.xml文件不仅包含<snapshot/>'s<timestamp/>和<buildNumber>要更新，而且还<snapshotVersion/>附加新条目。相反，发生的情况是，整个文件都重新生成，并且只有一个<snapshotVersion/>且只有<snapshot/>'s<timestamp/>和<buildNumber>正确更新。

我在这里缺少什么？为什么没有maven-metadata.xml正确生产？是否有我缺少的插件？这是 Gradle 中的错误吗？

此外，我在 Gradle 问题跟踪器中提出了问题#2882，希望从我们这边弄清楚这是一个错误、不完整的功能还是错误配置。

我也试过这个maven-publish插件，但是生成的maven-metadata.xml文件还是一样。