src/Utils/ASTDefinitionBuilder.php
private function getDeprecationReason($node)
    {
        $deprecated = Values::getDirectiveValues(Directive::deprecatedDirective(), $node);

        return $deprecated['reason'] ?? null;
    }
private function getDeprecationReason($node)
    {
        $deprecated = Values::getDirectiveValues(Directive::deprecatedDirective(), $node);

        return $deprecated['reason'] ?? null;
    }
Given a collection of directives, returns the string value for the
deprecation reason.

@param EnumValueDefinitionNode | FieldDefinitionNode $node

@return string