how does "com.google.zxing.client.android.SCAN" work in android?

I developed a BarcodeScanner app with ZXING library. for that I downloaded the complete library and added it to my proj and called an Intent with URI:"com.myproject.vinscan.client.android.SCAN". but later I found that, instead of downloading and including all packages of ZXING into our proj, we can just use the URI for Inetnt as "com.google.zxing.client.android.SCAN". My doubt is, how is it working without the libraries. It is working even in offline mode(without WIFI/GPRS). are the libraries included in the android SDK itself?

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