code: public static <T> Filter<T> or(final Filter<T> f1, final Filter<T> f2) {
  		return new Filter<T>() {
  			@Override
  			public boolean matches(Path.ID id, Content.Type<T> ct) {
  				return f1.matches(id, ct) || f2.matches(id, ct);
  			}
  			@Override
  			public boolean matchesSubpath(Path.ID id) {
  				return f1.matchesSubpath(id) || f2.matchesSubpath(id);
  			}
  			@Override
  			public String toString() {
  				return f1.toString() + "|" + f2.toString();
  			}
  		};
  	}
docs: Combine two filters together produce one filter whose items must be
  matched by at least one of the original filters.
  
  @param f1
  @param f2
  @return