code: public MediaType withParameter(String attribute, String value) {
      return withParameters(attribute, ImmutableSet.of(value));
    }
docs: <em>Replaces</em> all parameters with the given attribute with a single parameter with the
  given value. If multiple parameters with the same attributes are necessary use {@link
  #withParameters(String, Iterable)}. Prefer {@link #withCharset} for setting the {@code charset}
  parameter when using a {@link Charset} object.
  
  @throws IllegalArgumentException if either {@code attribute} or {@code value} is invalid