Version: 5.5
public ModelImporterClipAnimation[] clipAnimations ;

Description

Animation clips to split animation into. See Also: ModelImporterClipAnimation.

When you import a file for the first time clipAnimations will be always empty. If you need to populate clipAnimations before the first import you can use an AssetPostprocessor and override AssetPostprocessor.OnPreprocessAnimation.

public class CreateAnimationClip : AssetPostprocessor
{
    void OnPreprocessAnimation()
    {
        var modelImporter = assetImporter as ModelImporter;
        modelImporter.clipAnimations = modelImporter.defaultClipAnimations;
    }
}