code: public GVRAnimation setOffset(float startOffset)
      {
          if(startOffset<0 || startOffset>mDuration){
              throw new IllegalArgumentException("offset should not be either negative or greater than duration");
          }
          animationOffset = startOffset;
          mDuration =  mDuration-animationOffset;
          return this;
      }
docs: Sets the offset for the animation.
  
  @param startOffset animation will start at the specified offset value
  
  @return {@code this}, so you can chain setProperty() calls.
  @throws IllegalArgumentException
  If {@code startOffset} is either negative or greater than
  the animation duration