Clarification: Which import is the Replacement of BitmapRequestBuilder, DrawableRequestBuilder and GenericRequestBuilder in G3 to G4

Clarification: Which import is the Replacement of BitmapRequestBuilder, DrawableRequestBuilder and GenericRequestBuilder in G3 to G4

```
import com.bumptech.glide.BitmapRequestBuilder;
import com.bumptech.glide.DrawableRequestBuilder;
import com.bumptech.glide.GenericRequestBuilder;

private final DrawableRequestBuilder mGlideModelRequest;
private final BitmapRequestBuilder mGlideAvatarRequest;
private final BitmapRequestBuilder glideVideoThumbnailRequest;

mGlideModelRequest = Glide.with(context).from(Photo.class)
.transform(mCenterCrop)
.diskCacheStrategy(DiskCacheStrategy.DATA);

mGlideAvatarRequest = Glide.with(context).
from(Model.class)
.asBitmap()
.placeholder(R.drawable.emptyavatar)
.transform(mCenterCrop)
.diskCacheStrategy(DiskCacheStrategy.DATA);

glideVideoThumbnailRequest = Glide.with(context).
from(VideoThumbnail.class)
.asBitmap()
.transform(mCenterCrop)
.diskCacheStrategy(DiskCacheStrategy.DATA);

```