code: public static void sameSize(final Collection<?> collection1, final Collection<?> collection2, final String collection1Name, final String collection2Name) {
          notNull(collection1, collection1Name);
          notNull(collection2, collection2Name);
  
          if (collection1.size() != collection2.size()) {
              throw new IllegalArgumentException("expecting " + maskNullArgument(collection1Name) + " to have the same size as " + maskNullArgument(collection2Name));
          }
      }
docs: Checks that the collections have the same number of elements, otherwise throws an exception
  @param collection1 the first collection
  @param collection2 the second collection
  @param collection1Name the name of the first collection
  @param collection2Name the name of the second collection
  @throws IllegalArgumentException if collection1 or collection2 are null or if the collections don't agree on the number of elements