docs: public static String asString(Collection<?> collection) {
          if (collection == null) {
              return NULL;
          }
          StringBuilder builder = new StringBuilder();
          builder.append('[');
          boolean first = true;
          for (Object item : collection) {
              if (first) {
                  first = false;
              } else {
                  builder.append(',');
              }
              builder.append(asString(item));
          }
          builder.append(']');
          return builder.toString();
      }