code: public Request param(String name, Iterable<Object> values) {
          if (params == null) {
              params = new LinkedHashMap<String, Object>();
          }
          params.put(name, values);
          return this;
      }
docs: Set (or overwrite) a parameter with multiple values.
  <br>
  The parameter will be used to create a query string for GET-requests and as the body for POST-requests
  with MIME-type <code>application/x-www-form-urlencoded</code>.
  <br>
  If you use this method, you don't have to call {@link #multipleValues()}, but you should not mix
  using {@link #param(String, Object)} and this method for the same parameter name as this might cause
  unexpected behaviour or exceptions.
  
  @param name the name of the parameter (it's better to use only contain ASCII characters)
  @param values the values of the parameter; will be expanded to multiple valued parameters.
  @return <code>this</code> for method chaining (fluent API)
  @since 1.3.0