follow the tutorial:  https://github.com/flutter/fl...
 step to introduce flutter into an existing project 
in the completion step:
 
:
ERROR: Could not find method testImplementation() for arguments [junit:junit:4.12] on object of type org.gradle.api.internal.artifacts.dsl.dependencies.DefaultDependencyHandler.
flutterbuild.gradle
 
would like to ask how to modify it to introduce it correctly
