code: public static <T> Collection<T> notEmpty(Collection<T> array, String message) {
  		if (array == null || array.size() == 0) {
  			throw new IllegalArgumentException(message);
  		}
  		return array;
  	}
docs: Check if a collection is not null and not empty.
  If collection is null or empty, an {@link java.lang.IllegalArgumentException} is thrown.
  If collection is not null and not empty, it will be automatically returned.
  
  @param array Collection to check.
  @param message Exception message.
  @param <T> Type of array elements.
  @return Original collection.