code: public static <T1, T2> BiConsumer<T1, T2> spy2nd(BiConsumer<T1, T2> consumer, Box<T2> param2) {
          return spy(consumer, Box.<T1>empty(), param2);
      }
docs: Proxies a binary consumer spying for second parameter.
  
  @param <T1> the consumer first parameter type
  @param <T2> the consumer second parameter type
  @param consumer the consumer that will be spied
  @param param2 a box that will be containing the second spied parameter
  @return the proxied consumer