code: public static void notEmpty(final Collection<?> collection, final String collectionName) {
          notNull(collection, collectionName);
  
          if (collection.isEmpty()) {
              throw new IllegalArgumentException("expecting " + maskNullArgument(collectionName) + " to contain 1 or more elements");
          }
      }
docs: Check that a collection is not empty
  @param collection the collection to check
  @param collectionName the name of the collection
  @throws IllegalArgumentException if collection is null or if the collection is empty