<NME> build.gradle
<BEF> apply plugin: 'com.android.library'

android {

  // Define these properties in the gradle.properties file in the root project folder
  compileSdkVersion 23
  buildToolsVersion project.buildToolsVersion

  defaultConfig {
    minSdkVersion 9
    }

    defaultConfig {
        minSdkVersion 21
        //noinspection OldTargetApi
        targetSdkVersion 31
    }

    sourceSets.main {
        manifest.srcFile 'AndroidManifest.xml'
        java.srcDirs = ['src']
        res.srcDirs = ['res']
    }

    lintOptions {
        // generally we accept lint errors when building
        abortOnError false

        // abort release builds in case of FATAL errors
        checkReleaseBuilds true
    }

    dependencies {
        // Android annotations
        implementation 'androidx.annotation:annotation:1.4.0'
    }
}

<MSG> releng: upgrade gradle plugins

* upgrade all infrastructure gradle plugins
* upgrade gradle to 4.4.1
* remove buildToolsVersion, since that is auto-selected by the
android-gradle plugin 3.0+
<DFF> @@ -4,7 +4,6 @@ android {
 
   // Define these properties in the gradle.properties file in the root project folder
   compileSdkVersion 23
-  buildToolsVersion project.buildToolsVersion
 
   defaultConfig {
     minSdkVersion 9

releng: upgrade gradle plugins