public BookBuilder<P> paperColors(Map<PaperBuilder<?>, ColorBuilder<?>> paperColors) {
		verifyMutable();

		if (this.paperColors == null) {
			this.paperColors = new HashMap<PaperBuilder<?>, ColorBuilder<?>>();
		}
		if (paperColors != null) {
			for (Map.Entry<PaperBuilder<?>, ColorBuilder<?>> e : paperColors.entrySet()) {
				CollectionUtils.putItem(this.paperColors, e.getKey(), e.getValue());
			}
		}
		return this;
	}