def required_parameters
      required = {}
      @input_parameters.each_value { |v| required[v.name] = v if v.required? }
      required
    end
def required_parameters
      required = {}
      @input_parameters.each_value { |v| required[v.name] = v if v.required? }
      required
    end
Get an array of the names of all the required input parameters
 @return [Hash] Hash of WorkflowParameter input parameters which
   are required for this workflow