def add_default_parameter_values(self, sam_template):
parameter_definition = sam_template.get("<STR_LIT>", None)<EOL>if not parameter_definition or not isinstance(parameter_definition, dict):<EOL><INDENT>return self.parameter_values<EOL><DEDENT>for param_name, value in parameter_definition.items():<EOL><INDENT>if param_name not in self.parameter_values and isinstance(value, dict) and "<STR_LIT>" in value:<EOL><INDENT>self.parameter_values[param_name] = value["<STR_LIT>"]<EOL><DEDENT><DEDENT>
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