Android dependency 'androidx.core:core' has different version for 
the compile (1.0.0) and runtime (1.0.2) classpath. You should 
manually set the same version via DependencyResolution

android {
    compileSdkVersion 28

    defaultConfig {
        minSdkVersion 16
        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }
    lintOptions {
        disable 'InvalidPackage'
    }
    dependencies {
        implementation 'androidx.core:core:1.0.0'
        implementation 'androidx.annotation:annotation:1.0.0'
    }
}

q1deMacBook-Pro:~ q1$ flutter doctor -v
[✓] Flutter (Channel unknown, v1.12.13, on Mac OS X 10.14.5 18F2059, locale
    zh-Hans-CN)
    • Flutter version 1.12.13 at /Users/q1/flutter
    • Framework revision cf37c2cd07 (3 months ago), 2019-11-25 12:04:30 -0800
    • Engine revision b6b54fd606
    • Dart version 2.7.0

[✓] Android toolchain - develop for Android devices (Android SDK version 29.0.2)
    • Android SDK at /Users/q1/Library/Android/sdk
    • Android NDK location not configured (optional; useful for native profiling
      support)
    • Platform android-29, build-tools 29.0.2
    • ANDROID_HOME = /Users/q1/Library/Android/sdk
    • Java binary at: /Applications/Android
      Studio.app/Contents/jre/jdk/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build
      1.8.0_202-release-1483-b49-5587405)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 11.3)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Xcode 11.3, Build version 11C29
    • CocoaPods version 1.8.4

[✓] Android Studio (version 3.5)
    • Android Studio at /Applications/Android Studio.app/Contents
    • Flutter plugin version 42.1.1
    • Dart plugin version 191.8593
    • Java version OpenJDK Runtime Environment (build
      1.8.0_202-release-1483-b49-5587405)

[✓] Connected device (2 available)
    • Android SDK built for x86 • emulator-5554                        •
      android-x86 • Android 10 (API 29) (emulator)
    • iPhone 11 Pro Max         • 083FB0DB-0531-41FA-8C94-EADF5F884353 • ios
      • com.apple.CoreSimulator.SimRuntime.iOS-13-3 (simulator)

• No issues found!