dependencies {
    ...
+    implementation project(':rn-fetch-blob')                                                                      
}

include ':app'      
+ include ':rn-fetch-blob'                                                                                                  
+ project(':rn-fetch-blob').projectDir = new File(rootProject.projectDir, '../node_modules/rn-fetch-blob/android')                        

...
+ import com.RNFetchBlob.RNFetchBlobPackage;                                                                                 
...
protected List<ReactPackage> getPackages() {
      return Arrays.<ReactPackage>asList(
          new MainReactPackage(),
+         new RNFetchBlobPackage()                                                                                         
      );
    }
  };
...

dependencies {
    implementation 'com.facebook.react:react-native:+'
+   implementation 'com.squareup.okhttp3:okhttp:3.4.1'                                                                                           
-   //{RNFetchBlob_PRE_0.28_DEPDENDENCY}                                                                         
}