code: def add_default_parameter_values(self, sam_template):
          
  
          parameter_definition = sam_template.get("Parameters", None)
          if not parameter_definition or not isinstance(parameter_definition, dict):
              return self.parameter_values
  
          for param_name, value in parameter_definition.items():
              if param_name not in self.parameter_values and isinstance(value, dict) and "Default" in value:
                  self.parameter_values[param_name] = value["Default"]
docs: Method to read default values for template parameters and merge with user supplied values.
  
          Example:
          If the template contains the following parameters defined
  
          Parameters:
              Param1:
                  Type: String
                  Default: default_value
              Param2:
                  Type: String
                  Default: default_value
  
          And, the user explicitly provided the following parameter values:
  
          {
              Param2: "new value"
          }
  
          then, this method will grab default value for Param1 and return the following result:
  
          {
              Param1: "default_value",
              Param2: "new value"
          }
  
  
          :param dict sam_template: SAM template
          :param dict parameter_values: Dictionary of parameter values provided by the user
          :return dict: Merged parameter values