code: public GVRAnimationChannel findChannel(String boneName)
      {
          int boneId = mSkeleton.getBoneIndex(boneName);
          if (boneId >= 0)
          {
              return mBoneChannels[boneId];
          }
          return null;
      }
docs: Find the channel in the animation that animates the named bone.
  @param boneName  name of bone to animate.