upgraded to gradle 6 / gradle plugin 4

android/app/build.gradle

@@ -43,6 +43,7 @@ android {
         // Gradle plugin 4.0 desugaring features allow targeting older SDKs
         // but Flutter (as of v1.17.3) fails to run in release mode when using Gradle plugin 4.0:
         // https://github.com/flutter/flutter/issues/58247
+        // but there is a workaround (cf `afterEvaluate` section below)
         minSdkVersion 24
         targetSdkVersion 29 // same as compileSdkVersion
         versionCode flutterVersionCode.toInteger()
@@ -80,6 +81,22 @@ flutter {
     source '../..'
 }
 
+// workaround to https://github.com/flutter/flutter/issues/58247
+afterEvaluate {
+    android.productFlavors.all { flavor ->
+        def debugLintTask = tasks.findByName("lint${flavor.name.capitalize()}Debug")
+        def releaseLintTask = tasks.findByName("lint${flavor.name.capitalize()}Release")
+
+        if (debugLintTask != null) {
+            debugLintTask.dependsOn ':flutter:assemble'
+        }
+
+        if (releaseLintTask != null) {
+            releaseLintTask.dependsOn ':flutter:assemble'
+        }
+    }
+}
+
 repositories {
     maven {
         url "https://s3.amazonaws.com/repo.commonsware.com"

android/build.gradle

@@ -5,7 +5,7 @@ buildscript {
     }
 
     dependencies {
-        classpath 'com.android.tools.build:gradle:3.6.3'
+        classpath 'com.android.tools.build:gradle:4.0.0'
         classpath 'com.google.gms:google-services:4.3.3'
         classpath 'com.google.firebase:firebase-crashlytics-gradle:2.1.1'
     }

android/gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,6 @@
-#Tue Apr 21 13:20:37 KST 2020
+#Fri Jul 03 23:16:00 KST 2020
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-5.6.4-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-6.1.1-all.zip