code: @Override
  	public boolean apply(final Link link) {
  		final String sourceHost = link.source.getHost(), targetHost = link.target.getHost();
  		if (sourceHost == null) throw new IllegalArgumentException("URI \"" + link.source + "\" has no host");
  		if (targetHost == null) throw new IllegalArgumentException("URI \"" + link.target + "\" has no host");
  		// BURL hosts are always lower cased
  		return sourceHost.equals(targetHost);
  	}
docs: Apply the filter to a given link, returning true if source and target
  have the same {@linkplain java.net.URI#getHost() host}.
  
  @param link the link to be filtered.
  @return true if the host of the source and target of {@code link} are the same.