The plugin firebase_database requires a higher Android SDK version – Flutter

I got this error when i connect my flutter app with firebase rtdb

FAILURE: Build failed with an exception.

• What went wrong:
  Execution failed for task ‘:app:processDebugMainManifest’.

Manifest merger failed : uses-sdk:minSdkVersion 16 cannot be smaller than version 19 declared in library [:firebase_database] C:wmsflutterwarehouse_management_systembuildfirebase_databaseintermediatesmerged_manifestdebugAndroidManifest.xml as the library might be using APIs not available in 16
Suggestion: use a compatible library with a minSdk of at most 16,
or increase this project’s minSdk version to at least 19,
or use tools:overrideLibrary="io.flutter.plugins.firebase.database" to force usage (may lead to runtime failures)

• Try:

Run with –stacktrace option to get the stack trace.
Run with –info or –debug option to get more log output.
Run with –scan to get full insights.

• Get more help at https://help.gradle.org

But the problem is thatmy minsdk version is already 19 , i changed it in build.gradle script.

**compileSdkVersion 21

defaultConfig {

    minSdkVersion 19
    targetSdkVersion 21
}

compileSdkVersion flutter.compileSdkVersion
ndkVersion flutter.ndkVersion

**

Do you have any idea for this issue ?

Thanks in advance !