src/Schema/AST/DocumentAST.php
protected function typeExtensionUniqueKey(TypeExtensionNode $typeExtensionNode): string
    {
        $fieldNames = (new Collection($typeExtensionNode->fields))
            ->map(function ($field): string {
                return $field->name->value;
            })
            ->implode(':');

        return $typeExtensionNode->name->value.$fieldNames;
    }
protected function typeExtensionUniqueKey(TypeExtensionNode $typeExtensionNode): string
    {
        $fieldNames = (new Collection($typeExtensionNode->fields))
            ->map(function ($field): string {
                return $field->name->value;
            })
            ->implode(':');

        return $typeExtensionNode->name->value.$fieldNames;
    }
protected function typeExtensionUniqueKey ( TypeExtensionNode $ typeExtensionNode ) : string { $ fieldNames = ( new Collection ( $ typeExtensionNode -> fields ) ) -> map ( function ( $ field ) : string { return $ field -> name -> value ; } ) -> implode ( ':' ) ; return $ typeExtensionNode -> name -> value . $ fieldNames ; }
Return a unique key that identifies a type extension.

@param  \GraphQL\Language\AST\TypeExtensionNode  $typeExtensionNode
@return string
Return a unique key that identifies a type extension .