Determine a suitable default value for minSdkVersion

The minSdkVersion is currently set to 17 (Android-4 2012).

When building the app with a common plugin like @nativescript/background-http the build will fail.

Execution failed for task ':app:processDebugMainManifest'.
Manifest merger failed : uses-sdk:minSdkVersion 17 cannot be smaller than version 21 declared in library [net.gotev:uploadservice:4.7.0] /Users/ianbrindley/.gradle/caches/transforms-3/24fa1312ea1be6efbab27240facdcfb1/transformed/jetified-uploadservice-4.7.0/AndroidManifest.xml as the library might be using APIs not available in 17
        Suggestion: use a compatible library with a minSdk of at most 17,
                or increase this project's minSdk version to at least 21,
                or use tools:overrideLibrary="net.gotev.uploadservice" to force usage (may lead to runtime failures)

Instead I have to add additional configuration to gradle to get this plugin to work.

I suggest that the minSdkVersion is set to 21.

从定义默认 minSdkVersion 的 Android 构建配置开始，使用 @nativescript/background-http 重现 manifest-merger 失败。检查将默认值从 17 更改为 21 的兼容性影响，然后验证插件无需额外的 Gradle 配置即可构建成功。项目使用约定的默认值且报告的构建成功，即表示完成。