Got error in Android studio.. I am creating android app of wallpaper with admob and push notification. Please help me : Error:Execution failed for task ':app:processDebugManifest'.
> Manifest merger failed : uses-sdk:minSdkVersion 14 cannot be smaller than version 15 declared in library [com.onesignal:OneSignal:3.8.1] G:\gradle-4.4.1\bin\caches\transforms-1\files-1.1\OneSignal-3.8.1.aar\4992f150d9197af17fab12064aa2676a\AndroidManifest.xml as the library might be using APIs not available in 14
  	Suggestion: use a compatible library with a minSdk of at most 14,
  		or increase this project's minSdk version to at least 15,
  		or use tools:overrideLibrary="com.onesignal" to force usage (may lead to runtime failures)