code: public HttpMediaType setParameter(String name, String value) {
      if (value == null) {
        removeParameter(name);
        return this;
      }
  
      Preconditions.checkArgument(
          TOKEN_REGEX.matcher(name).matches(), "Name contains reserved characters");
      cachedBuildResult = null;
      parameters.put(name.toLowerCase(Locale.US), value);
      return this;
    }
docs: Sets the media parameter to the specified value.
  
  @param name case-insensitive name of the parameter
  @param value value of the parameter or {@code null} to remove