Workspace\project\app\build\intermediates\res\merged\debug\values\values.xml Error:(145) Attribute "background" has already been defined Error:Execution failed for task ':app:processDebugResources'.
com.android.ide.common.process.ProcessException: org.gradle.process.internal.ExecException: Process 'command 'C:\Users\Redixbit\AppData\Local\Android\Sdk\build-tools\23.0.3\aapt.exe'' finished with non-zero exit value 1
This exception has nothing to do with OneSignal, please do clean your project and check your project properties in Gradle file then do a clean build and run.