我已经在github上创建了一个android库，并对其进行了一些修复，现在我想获得一个快照版本作为我自己项目的依赖项，但jitpack.io中的构建任务失败了

* What went wrong:
Execution failed for task ':project_name:signReleasePublication'.
> path may not be null or empty string. path=''

字符串
该项目有publish-mavencentral.gradle脚本设置为发布任务与签名属性读取从一个文件或环境变量，我猜是造成问题

ext["signing.keyId"] = ''
ext["signing.password"] = ''
ext["signing.secretKeyRingFile"] = ''
ext["ossrhUsername"] = ''
ext["ossrhPassword"] = ''
ext["sonatypeStagingProfileId"] = ''

File secretPropsFile = project.rootProject.file('local.properties')
if (secretPropsFile.exists()) {
    Properties p = new Properties()
    p.load(new FileInputStream(secretPropsFile))
    p.each { name, value ->
        ext[name] = value
    }
} else {
    ext["signing.keyId"] = System.getenv('SIGNING_KEY_ID')
    ext["signing.password"] = System.getenv('SIGNING_PASSWORD')
    ext["signing.secretKeyRingFile"] = System.getenv('SIGNING_SECRET_KEY_RING_FILE')
    ext["ossrhUsername"] = System.getenv('OSSRH_USERNAME')
    ext["ossrhPassword"] = System.getenv('OSSRH_PASSWORD')
    ext["sonatypeStagingProfileId"] = System.getenv('SONATYPE_STAGING_PROFILE_ID')
}

signing {
    sign publishing.publications
}

型
已尝试添加required()指令，但不起作用

signing {
    required { hasProperty("signing.keyId") }
    sign publishing.publications
}

型
如果属性为空，如何跳过签名？