code: public static <T1, T2> BiConsumer<T1, T2> spy1st(BiConsumer<T1, T2> consumer, Box<T1> param1) {
          return spy(consumer, param1, Box.<T2>empty());
      }
docs: Proxies a binary consumer spying for first parameter.
  
  @param <T1> the consumer first parameter type
  @param <T2> the consumer second parameter type
  @param consumer the consumer that will be spied
  @param param1 a box that will be containing the first spied parameter
  @return the proxied consumer