android.support.v4.content.FileProvider not found

I am trying to upgrade a working old app to support Android API 26, and one of the thing I need to use is android.support.v4.content.FileProvider – but it was not found.

    <provider
        android:name="android.support.v4.content.FileProvider"
        android:authorities="${applicationId}.fileprovider"
        android:exported="false"
        android:grantUriPermissions="true">
        <meta-data
            android:name="android.support.FILE_PROVIDER_PATHS"
            android:resource="@xml/file_paths" />
    </provider>

Due to the early Android build, the gradle file seems simple. Is it as simple as adding a dependency? I have look around and some suggested adding a multidex which I don’t understand. Any help is appreciated, thank you!

android {
    compileSdkVersion 26
    buildToolsVersion '26.0.2'

    defaultConfig {
        applicationId "virtualgs.spaint"
        minSdkVersion 22
        targetSdkVersion 26
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.txt'
        }
    }
}

Answer

add compile 'com.android.support:support-v4:26.1.0' to build.gradle file in app module.