Could not resolve io.flutter:flu

打开build.gradle文件
 
buildscript {
    ext.kotlin_version = '1.3.50'
    repositories {
        google()
        jcenter()
        maven { url "http://download.flutter.io" }
    }
 
    dependencies {
        classpath 'com.android.tools.build:gradle:3.5.0'
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
    }
}
 
allprojects {
    repositories {
        google()
        jcenter()
        maven { url "http://download.flutter.io" }
    }