code: protected float computeUniformPadding(final CacheDataSet cache) {
          float axisSize = getViewPortSize(getOrientationAxis());
          float totalPadding = axisSize - cache.getTotalSize();
          float uniformPadding = totalPadding > 0 && cache.count() > 1 ?
                  totalPadding / (cache.count() - 1)  : 0;
          return uniformPadding;
      }
docs: Compute the proportional padding for all items in the cache
  @param cache Cache data set
  @return the uniform padding amount