code: @Nonnull
    public Result header(final String name, final Iterable<Object> values) {
      requireNonNull(name, "Header's name is required.");
      requireNonNull(values, "Header's values are required.");
      setHeader(name, values);
      return this;
    }
docs: Sets a response header with the given name and value. If the header had already been set,
  the new value overwrites the previous one.
  
  @param name Header's name.
  @param values Header's values.
  @return This content.