title: Retrofit 2.4.0 with Gradle plugin 3.1.2
body: <p>I have a very simple question. I'm an Android Developer returning back to development after a 6 months break and as usual everything has changed apparently. Here is my question:</p>
  
  <ul>
  <li>Start a new Android project on Android Studio 3.1.2</li>
  <li>Default Gradle plugin is 3.1.2</li>
  <li>Added retrofit2 dependency to app's build.gradle  </li>
  </ul>
  
  <p><code>implementation 'com.squareup.retrofit2:retrofit:2.4.0'</code></p>
  
  <ul>
  <li>Started gradle sync</li>
  </ul>
  
  <blockquote>
    <p>Unable to resolve dependency for ':app@debug/compileClasspath': Could
    not resolve com.squareup.retrofit2:retrofit:2.4.0. Open File Show
    Details</p>
    
    <p>Unable to resolve dependency for
    ':app@debugAndroidTest/compileClasspath': Could not resolve
    com.squareup.retrofit2:retrofit:2.4.0. Open File Show Details</p>
    
    <p>Unable to resolve dependency for
    ':app@debugUnitTest/compileClasspath': Could not resolve
    com.squareup.retrofit2:retrofit:2.4.0. Open File Show Details</p>
    
    <p>Unable to resolve dependency for ':app@release/compileClasspath':
    Could not resolve com.squareup.retrofit2:retrofit:2.4.0. Open File
    Show Details</p>
    
    <p>Unable to resolve dependency for
    ':app@releaseUnitTest/compileClasspath': Could not resolve
    com.squareup.retrofit2:retrofit:2.4.0. Open File Show Details</p>
  </blockquote>
  
  <p>I read the whole article about Gradle plugin 3 migration. It is no help.</p>
  
  <p>Project build.gradle</p>
  
  <pre><code>// Top-level build file where you can add configuration options common to all sub-projects/modules.
  
  buildscript {
  
      repositories {
          google()
          jcenter()
      }
      dependencies {
          classpath 'com.android.tools.build:gradle:3.1.2'
          // NOTE: Do not place your application dependencies here; they belong
          // in the individual module build.gradle files
      }
  }
  
  allprojects {
      repositories {
          google()
          jcenter()
      }
  }
  
  task clean(type: Delete) {
      delete rootProject.buildDir
  }
  </code></pre>
  
  <p>app level build.gradle</p>
  
  <pre><code>apply plugin: 'com.android.application'
  
  android {
      compileSdkVersion 27
      buildToolsVersion "27.0.3"
      defaultConfig {
          applicationId "com.xyz.xyz"
          minSdkVersion 15
          targetSdkVersion 27
          versionCode 1
          versionName "1.0"
          testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
      }
      buildTypes {
          release {
              minifyEnabled false
              proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
          }
  
      }
  }
  
  dependencies {
      implementation fileTree(dir: 'libs', include: ['*.jar'])
      implementation 'com.android.support:appcompat-v7:27.1.1'
      implementation 'com.android.support.constraint:constraint-layout:1.1.0'
      implementation 'com.squareup.retrofit2:retrofit:2.4.0'
      testImplementation 'junit:junit:4.12'
      androidTestImplementation 'com.android.support.test:runner:1.0.2'
      androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
  }
  </code></pre>