问题：

A problem occurred evaluating project ':javassist'.
> Plugin with id 'maven' not found.
Caused by: org.gradle.api.plugins.UnknownPluginException: Plugin with id 'maven' not found.

原因：

Android Studio 升级到Arctic Fox版本后，Gradle及其插件的版本默认是7.0及以上了；在Gradle 7.0以及以后的版本中maven插件已经被移除了，改为使用"maven-publish"

解决办法：

• apply plugin: 'maven' 改为 apply plugin: 'maven-publish'

• uploadArchives 需要改为新的写法publishing ：
  旧：

  uploadArchives{
      repositories.mavenDeployer {
          pom.groupId = 'com.test'
          pom.artifactId = 'test'
          pom.version = '1.0.0'
          repository(url: uri('../repo'))
      }
  }
  

  新：

  publishing {
      publications {
          maven(MavenPublication) {
              groupId = 'com.test'
              artifactId = 'test'
              version = '1.0.0'
              from components.java
          }
      }
  
      repositories {
          maven {
              // change to point to your repo, e.g. http://my.org/repo
              url = '../repo'
          }
      }
  }
  

• 修改后完整build.gradle参考：

  apply plugin: 'groovy'
  apply plugin: 'maven-publish'
  repositories {
      mavenCentral()
  }
  dependencies {
      implementation gradleApi()
      implementation localGroovy()
      implementation 'com.android.tools.build:gradle:3.1.3'
      implementation 'org.javassist:javassist:3.20.0-GA'
  }
  publishing {
      publications {
          maven(MavenPublication) {
              groupId = 'com.javassist'
              artifactId = 'modify'
              version = '1.0.0'
              from components.java
          }
      }
      repositories {
          maven {
              // change to point to your repo, e.g. http://my.org/repo
              url = '../repo'
          }
      }
  }
  sourceCompatibility = "7"
  targetCompatibility = "7"
  
  

参考文档

https://docs.gradle.org/7.0/userguide/publishing_maven.html

其他相关

Gradle命令中找到publish命令即可发布插件