Opensearch plugin build always failed with this error

Versions (relevant - OpenSearch/Dashboard/Server OS/Browser):
Gradle version: 6.6.1

Java version:

Describe the issue:
➜ gradle build

FAILURE: Build failed with an exception.

  • Where:
    Build file ‘/Users/qiafan/Desktop/custom-settings/build.gradle’ line: 30

  • What went wrong:
    A problem occurred evaluating root project ‘custom-settings’.

Plugin with id ‘opensearch.opensearchplugin’ not found.

cat build.gradle

apply plugin: 'java'
apply plugin: 'idea'
apply plugin: 'eclipse'
apply plugin: 'opensearch.opensearchplugin'
apply plugin: 'opensearch.pluginzip'

def pluginName = 'qq-tt-plugin'
def pluginDescription = 'qq tt onboarding'
group = 'aa.bb.qq'
version = '1.2.4'


// TODO: enable
testingConventions.enabled = false
forbiddenApis.ignoreFailures = false

dependencyLicenses.enabled = false
thirdPartyAudit.enabled = false
forbiddenApisTest.ignoreFailures = true
validateNebulaPom.enabled = false
loggerUsageCheck.enabled = false

publishing {
    publications {
        pluginZip(MavenPublication) { publication ->
            pom {
                name = pluginName
                description = pluginDescription
                licenses {
                    license {
                        name = "The Apache License, Version 2.0"
                        url = "http://www.apache.org/licenses/LICENSE-2.0.txt"
                    }
                }
                developers {
                    developer {
                        name = "OpenSearch-tt-Plugin"
                        url = "some_url"
                    }
                }
            }
        }
    }
}

opensearchplugin {
    name
    description pluginDescription
    classname 'com.tt.qq.plugin.ttPlugin'
    licenseFile rootProject.file('LICENSE.txt')
    noticeFile rootProject.file('NOTICE.txt')
}

buildscript {
    ext {
        opensearch_version = System.getProperty("opensearch.version", "1.2.4")
    }

    repositories {
        mavenLocal()
        maven { url "https://aws.oss.sonatype.org/content/repositories/snapshots" }
        mavenCentral()
        maven { url "https://plugins.gradle.org/m2/" }
    }

    dependencies {
        classpath "org.opensearch.gradle:build-tools:${opensearch_version}"
        classpath "org.apache.logging.log4j:log4j-1.2-api:2.17.1"
    }
}

repositories {
    mavenLocal()
    maven { url "https://aws.oss.sonatype.org/content/repositories/snapshots" }
    mavenCentral()
    maven { url "https://plugins.gradle.org/m2/" }
}

gradle --scan
https://scans.gradle.com/s/53aepexdny6ea/console-log?anchor=30&page=1

I cannot find opensearchplugin in the plugin repo.

May I know where is it stored?