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https://github.com/disneystreaming/smithy-translate

json-schema openapi protobuf smithy swagger

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Host: GitHub
URL: https://github.com/disneystreaming/smithy-translate
Owner: disneystreaming
License: other
Created: 2022-08-09T15:55:28.000Z (almost 2 years ago)
Default Branch: main
Last Pushed: 2024-05-05T12:08:56.000Z (about 2 months ago)
Last Synced: 2024-05-15T09:01:28.970Z (about 2 months ago)
Topics: json-schema, openapi, protobuf, smithy, swagger
Language: Scala
Homepage:
Size: 1.01 MB
Stars: 50
Watchers: 6
Forks: 12
Open Issues: 3
Metadata Files:
- Readme: README.md
- License: LICENSE

Lists

awesome-smithy - Smithy to Protobuf - smithy-translate (see above) (Model Converters / Server Code Generators)

README

# Smithy Translate

Tooling that enables converting to and from Smithy.

_Note: this library is published to work on Java 8 and above. However, you will need to use Java 11 or above to work on the library as a contributor. This is due to some of the build flags that we use._

## Table of Contents

- [formatter](#formatter)
- [CLI Usage](#cli-usage)
- [Capabilities and Design](#capabilities-and-design)
- [Alloy](#alloy)
- [CLI](#cli)
- [Installation](#installation)
- [OpenAPI](#openapi)
- [CLI Usage](#cli-usage-1)
- [Capabilities and Design](#capabilities-and-design-1)
- [Primitives](#primitives)
- [Aggregate Shapes](#aggregate-shapes)
- [Structure](#structure)
- [Structures with Mixins](#structures-with-mixins)
- [Untagged Union](#untagged-union)
- [Tagged Union](#tagged-union)
- [Discriminated Union](#discriminated-union)
- [List](#list)
- [Set](#set)
- [Map](#map)
- [Constraints](#constraints)
- [Enum](#enum)
- [Pattern](#pattern)
- [Service Shapes](#service-shapes)
- [Basic Service](#basic-service)
- [Service with Error Responses](#service-with-error-responses)
- [Operation with headers](#operation-with-headers)
- [Operation with multiple content types](#operation-with-multiple-content-types)
- [Extensions](#extensions)
- [JSON Schema](#json-schema)
- [CLI Usage](#cli-usage-2)
- [Differences from OpenAPI](#differences-from-openapi)
- [Default Values](#default-values)
- [Null Values](#null-values)
- [Maps](#maps)
- [Protobuf](#protobuf)
- [CLI Usage](#cli-usage-3)
- [Capabilities and Design](#capabilities-and-design-2)
- [Options](#options)
- [Stringly typed options](#stringly-typed-options)
- [Example](#example)

## formatter

### CLI Usage

The `smithytranslate` CLI will recursively go through all child directories of the
input directory provided and format any Smithy files it finds. The output

```
> smithytranslate format --help

Usage: smithytranslate format [--no-clobber] ...

validates and formats smithy files

Options and flags:
--help
Display this help text.
--no-clobber
dont overwrite existing file instead create a new file with the word 'formatted' appended so test.smithy -> test_formatted.smithy
```

### Capabilities and Design
- The formatter is based off the ABNF defined at [Smithy-Idl-ABNF](https://smithy.io/2.0/spec/idl.html#smithy-idl-abnf)
- The formatter assumes the file is a valid Smithy file and must be able to pass the Model Assembler validation , otherwise it will return an error
- use --no-clobber to create a new file to avoid overwriting the original file
- actual formatting rules are still WIP and will be updated as the formatter is developed

## Alloy

Throughout smithytranslate you will see references to [alloy](https://github.com/disneystreaming/alloy). Alloy is a lightweight library that houses some common smithy shapes that are used across our open source projects such as [smithy4s](https://github.com/disneystreaming/smithy4s). This is to provide better interoperability between our tools at a lower cost to end users.

## CLI

### Installation

You will need to [install coursier](https://get-coursier.io/docs/cli-installation), an artifact fetching library, in order to install the CLI.

```
coursier install --channel https://disneystreaming.github.io/coursier.json smithytranslate
```

Run `smithytranslate --help` for usage information.

## OpenAPI

### CLI Usage

The `smithytranslate` CLI will recursively go through all child directories of the
input directory provided and convert any openapi files ending with an extension of `yaml`,
`yml`, or `json`.

```
> smithytranslate openapi-to-smithy --help

Usage: smithytranslate openapi-to-smithy --input [--input ]... [--verboseNames] [--failOnValidationErrors] [--useEnumTraitSyntax] [--outputJson]

Take Open API specs as input and produce Smithy files as output.

Options and flags:
--help
Display this help text.
--input , -i
input source files
--verbose-names
If set, names of shapes not be simplified and will be as verbose as possible
--validate-input
If set, abort the conversion if any input specs contains a validation error
--validate-output
If set, abort the conversion if any produced smithy spec contains a validation error
--enum-trait-syntax
output enum types with the smithy v1 enum trait (deprecated) syntax
--json-output
changes output format to be json representations of the smithy models
```

Run `smithytranslate openapi-to-smithy --help` for more usage information.

### Capabilities and Design

Because Smithy is a more constrained format than OpenAPI, this conversion is _partial_.
This means that a best effort is made to translate all possible aspects of OpenAPI into
Smithy and errors are outputted when something cannot be translated. When errors are
encountered, the conversion still makes a best effort at converting everything else.
This way, as much of the specification will be translated automatically and the user
can decide how to translate the rest.

OpenAPI 2.x and 3.x are supported as input formats to this converter.

Below are examples of how Smithy Translate converts various OpenAPI constructs into
Smithy.

#### Primitives

| OpenAPI Base Type | OpenAPI Format
| -----------------
| string |
| string | timestamp
| string | date-time
| string | date
| string | uuid
| string | binary
| string | byte
| string | password
| number | float
| number | double
| number | double
| number |
| integer | int16
| integer |
| integer | int32
| integer | int64
| boolean |
| object | Smithy Shape | Smithy Trait(s) | | ------------------ | ------------ | ----------------------------- | | String | | | Timestamp | | | Timestamp | @timestampFormat("date-time") | | String | alloy#dateFormat | | alloy#UUID | | | Blob | | | Blob | | | String | @sensitive | | Float | | | Double | | | Double | | | Double | | | Short | | | Integer | | | Integer | | | Long | | | Boolean | | | (empty properties) | Document | |

#### Aggregate Shapes

##### Structure

OpenAPI:
```yaml
openapi: '3.0.'
info:
title: doc
version: 1.0.0
paths: {}
components:
schemas:
Testing:
type: object
properties:
myString:
type: string
my_int:
type: integer
required:
- myString
```

Smithy:
```smithy
structure Testing {
@required
myString: String
my_int: Integer
}
```

Required properties and nested structures are both supported.

Any properties in the input structure that begin with a number will be prefixed by the letter `n`. This is because smithy does not allow for member names to begin with a number. You can change this with post-processing if you want a different change to be made to names of this nature. Note that this extra `n` will not impact JSON encoding/decoding because we also attach the [JsonName Smithy trait](https://awslabs.github.io/smithy/2.0/spec/protocol-traits.html#jsonname-trait) to these properties. The same thing happens if the member name contains a hyphen. In this case, hyphens are replaced with underscores and a `jsonName` trait is once again added. Note that if the field is a header or query parameter, the `jsonName` annotation is not added since `httpHeader` or `httpQuery` is used instead.

OpenAPI:
```yaml
openapi: '3.0.'
info:
title: doc
version: 1.0.0
paths: {}
components:
schemas:
Testing:
type: object
properties:
12_twelve:
type: string
X-something:
type: string
```

Smithy:
```smithy
structure Testing {
@jsonName("12_twelve")
n12_twelve: String
@jsonName("X-something")
X_something: String
}
```

##### Structures with Mixins

Smithy Translate will convert allOfs from OpenAPI into structures with mixins in smithy where possible. AllOfs in OpenAPI have references to other types which compose the current type. We refer to these as "parents" or "parent types" below. There are three possibilities when converting allOfs to smithy shapes:

1. The parent structures are only ever used as mixins

OpenAPI:
```yaml
openapi: '3.0.'
info:
title: doc
version: 1.0.0
paths: {}
components:
schemas:
One:
type: object
properties:
one:
type: string
Two:
type: object
properties:
two:
type: string
Three:
type: object
allOf:
- $ref: "#/components/schemas/One"
- $ref: "#/components/schemas/Two"
```

Smithy:
```smithy
@mixin
structure One {
one: String
}

@mixin
structure Two {
two: String
}

structure Three with [One, Two] {}
```

Here we can see that both parents, `One` and `Two` are converted into mixins and used as such on `Three`.

2. The parents structures are used as mixins and referenced as member targets

OpenAPI:
```yaml
openapi: '3.0.'
info:
title: doc
version: 1.0.0
paths: {}
components:
schemas:
One:
type: object
properties:
one:
type: string
Two:
type: object
allOf:
- $ref: "#/components/schemas/One"
Three:
type: object
properties:
one:
$ref: "#/components/schemas/One"
```

Smithy:
```smithy
@mixin
structure OneMixin {
one: String
}

structure One with [OneMixin] {}

structure Two with [OneMixin] {}

structure Three {
one: One
}
```

Here `One` is used as a target of the `Three$one` member and is used as a mixin in the `Two` structure. Since smithy does not allow mixins to be used as targets, we have to create a separate mixin shape, `OneMixin` which is used as a mixin for `One` which is ultimately what we use for the target in `Three`.

3. One of the parents is a document rather than a structure

OpenAPI:
```yaml
openapi: '3.0.'
info:
title: doc
version: 1.0.0
paths: {}
components:
schemas:
One:
type: object
properties: {}
Two:
type: object
properties:
two:
type: string
Three:
type: object
allOf:
- $ref: "#/components/schemas/One"
- $ref: "#/components/schemas/Two"
```

Smithy:
```smithy
document One

structure Two {
two: String
}

document Three
```

In this case, no mixins are created since none are ultimately used. Since `One` is translated to a document, `Three` must also be a document since it has `One` as a parent shape. As such, `Two` is never used as a mixin.

##### Untagged Union

The majority of `oneOf` schemas in OpenAPI represent untagged unions.
As such, they will be tagged with the `alloy#untagged`
trait. There are two exceptions to this: tagged unions and discriminated
unions, shown in later examples.

OpenAPI:
```yaml
openapi: '3.0.'
info:
title: doc
version: 1.0.0
paths: {}
components:
schemas:
Cat:
type: object
properties:
name:
type: string
Dog:
type: object
properties:
breed:
type: string
TestUnion:
oneOf:
- $ref: '#/components/schemas/Cat'
- $ref: '#/components/schemas/Dog'
```

Smithy:
```smithy
use alloy#untagged

structure Cat {
name: String
}

structure Dog {
breed: String
}

@untagged
union TestUnion {
Cat: Cat,
Dog: Dog
}
```

##### Tagged Union

Smithy Translate will convert a `oneOf` to a tagged union IF
each of the branches of the `oneOf` targets a structure where
each of those structures contains a single required property.
Note that unions in smithy are tagged by default, so there is
no trait annotation required here.

OpenAPI:
```yaml
openapi: '3.0.'
info:
title: doc
version: 1.0.0
paths: {}
components:
schemas:
Number:
type: object
properties:
num:
type: integer
required:
- num
Text:
type: object
properties:
txt:
type: string
required:
- txt
TestUnion:
oneOf:
- $ref: '#/components/schemas/Number'
- $ref: '#/components/schemas/Text'
```

Smithy:
```smithy
structure Number {
@required
num: Integer,
}

structure Text {
@required
txt: String,
}

union TestUnion {
num: Integer,
txt: String
}
```

Although `TestUnion` is a tagged union that can be represented by directly
targeting the `Integer` and `String` types, `Text` and `Number` are still rendered.
This is because they are top-level schemas and could be used elsewhere.

##### Discriminated Union

A `oneOf` will be converted to a discriminated union IF it
contains the `discriminator` field. Discriminated unions in
Smithy will be denoted using the `alloy#discriminated`
trait. The discriminated trait contains the name of the property
that is used as the discriminator.

OpenAPI:
```yaml
openapi: '3.0.'
info:
title: doc
version: 1.0.0
paths: {}
components:
schemas:
Cat:
type: object
properties:
name:
type: string
pet_type:
type: string
Dog:
type: object
properties:
breed:
type: string
pet_type:
type: string
TestUnion:
oneOf:
- $ref: '#/components/schemas/Cat'
- $ref: '#/components/schemas/Dog'
discriminator:
propertyName: pet_type
```

Smithy:
```smithy
use alloy#discriminated

structure Cat {
name: String,
}

structure Dog {
breed: String,
}

@discriminated("pet_type")
union TestUnion {
Cat: Cat,
Dog: Dog
}
```

##### List

OpenAPI:
```yaml
openapi: '3.0.'
info:
title: doc
version: 1.0.0
paths: {}
components:
schemas:
StringArray:
type: array
items:
type: string
```

Smithy:
```smithy
list StringArray {
member: String
}
```

##### Set

OpenAPI:
```yaml
openapi: '3.0.'
info:
title: doc
version: 1.0.0
paths: {}
components:
schemas:
StringSet:
type: array
items:
type: string
uniqueItems: true
```

Smithy:
```smithy
@uniqueItems
list StringSet {
member: String
}
```

##### Map

OpenAPI:
```yaml
openapi: '3.0.'
info:
title: doc
version: 1.0.0
paths: {}
components:
schemas:
StringStringMap:
type: object
additionalProperties:
type: string
```

Smithy:
```smithy
map StringStringMap {
key: String,
value: String
}
```

#### Constraints

##### Enum

Enums can be translated to either Smithy V1 or V2 syntax. You can control this using the `useEnumTraitSyntax` CLI flag.

OpenAPI:
```yaml
openapi: '3.0.'
info:
title: doc
version: 1.0.0
paths: {}
components:
schemas:
Color:
type: string
enum:
- red
- green
- blue
```

Smithy:
```smithy
enum Color {
red
green
blue
}
```

Or if using the `useEnumTraitSyntax` flag:

```smithy
@enum([
{value: "red"},
{value: "green"},
{value: "blue"}
])
string Color
```

##### Pattern

OpenAPI:
```yaml
openapi: '3.0.'
info:
title: doc
version: 1.0.0
paths: {}
components:
schemas:
MyString:
type: string
pattern: '^\d{3}-\d{2}-\d{4}$'
```

Smithy:
```smithy
@pattern("^\\d{3}-\\d{2}-\\d{4}$")
string MyString
```

_Note that `length`, `range`, and `sensitive` traits are also supported,
as indicated in the primitives table above._

#### Service Shapes

##### Basic Service

OpenAPI:
```yaml
openapi: '3.0.'
info:
title: doc
version: 1.0.0
paths:
/test:
post:
operationId: testOperationId
requestBody:
required: true
content:
application/json:
schema:
$ref: '#/components/schemas/ObjectIn'
responses:
'200':
description: test
content:
application/json:
schema:
$ref: '#/components/schemas/ObjectOut'
components:
schemas:
ObjectIn:
type: object
properties:
s:
type: string
required:
- s
ObjectOut:
type: object
properties:
sNum:
type: integer
```

If provided, such as above, the `operationId` will be used
to inform the naming of the operation and the various shapes it
contains.

Smithy:
```smithy
use smithytranslate#contentType

service FooService {
operations: [TestOperationId]
}

@http(method: "POST", uri: "/test", code: 200)
operation TestOperationId {
input: TestOperationIdInput,
output: TestOperationId200
}

structure ObjectIn {
@required
s: String
}

structure ObjectOut {
sNum: Integer
}

structure TestOperationId200 {
@httpPayload
@required
@contentType("application/json")
body: ObjectOut
}

structure TestOperationIdInput {
@httpPayload
@required
@contentType("application/json")
body: ObjectIn
}
```

##### Service with Error Responses

OpenAPI:
```yaml
openapi: '3.0.'
info:
title: doc
version: 1.0.0
paths:
/test:
get:
operationId: testOperationId
responses:
'200':
description: test
content:
application/json:
schema:
$ref: '#/components/schemas/Object'
'404':
description: test
content:
application/json:
schema:
type: object
properties:
message:
type: string
components:
schemas:
Object:
type: object
properties:
s:
type: string
required:
- s
```

Smithy:
```smithy
use smithytranslate#contentType

service FooService {
operations: [TestOperationId]
}

@http(method: "GET", uri: "/test", code: 200)
operation TestOperationId {
input: Unit,
output: TestOperationId200,
errors: [TestOperationId404]
}

structure Object {
@required
s: String
}

@error("client")
@httpError(404)
structure TestOperationId404 {
@httpPayload
@required
@contentType("application/json")
body: Body
}

structure Body {
message: String
}

structure TestOperationId200 {
@httpPayload
@required
@contentType("application/json")
body: Object
}
```

##### Operation with headers

OpenAPI:
```yaml
openapi: '3.0.'
info:
title: doc
version: 1.0.0
paths:
/test:
get:
operationId: testOperationId
parameters:
- in: header
name: X-username
schema:
type: string
responses:
'200':
description: test
headers:
X-RateLimit-Limit:
schema:
type: integer
content:
application/json:
schema:
$ref: '#/components/schemas/Object'
components:
schemas:
Object:
type: object
properties:
s:
type: string
required:
- s
```

Smithy:
```smithy
use smithytranslate#contentType

service FooService {
operations: [TestOperationId]
}

@http(method: "GET", uri: "/test", code: 200)
operation TestOperationId {
input: TestOperationIdInput,
output: TestOperationId200
}

structure TestOperationIdInput {
@httpHeader("X-username")
X_username: String
}

structure Object {
@required
s: String,
}

structure TestOperationId200 {
@httpPayload
@required
@contentType("application/json")
body: Object,
@httpHeader("X-RateLimit-Limit")
X_RateLimit_Limit: Integer
}
```

##### Operation with multiple content types

Operations in OpenAPI may contain more than one
content type. This is represented in smithy using a
`union` with a special `contentTypeDiscriminated` trait.
This trait indicates that the members of the union are
discriminated from one another using the `Content-Type`
header. Each member of the union is annotated with the `contentType`
trait. This trait indicates which content type refers to each
specific branch of the union.

OpenAPI:
```yaml
openapi: '3.0.'
info:
title: doc
version: 1.0.0
paths:
/test:
post:
operationId: testOperationId
requestBody:
required: true
content:
application/octet-stream:
schema:
type: string
format: binary
application/json:
schema:
type: object
properties:
s:
type: string
responses:
'200':
description: test
content:
application/octet-stream:
schema:
type: string
format: binary
application/json:
schema:
type: object
properties:
s:
type: string
```

Smithy:
```smithy
use smithytranslate#contentTypeDiscriminated
use smithytranslate#contentType

service FooService {
operations: [TestOperationId]
}

@http(method: "POST", uri: "/test", code: 200)
operation TestOperationId {
input: TestOperationIdInput,
output: TestOperationId200
}

structure TestOperationIdInput {
@httpPayload
@required
body: TestOperationIdInputBody
}

structure TestOperationId200 {
@httpPayload
@required
body: TestOperationId200Body
}

@contentTypeDiscriminated
union TestOperationId200Body {
@contentType("application/octet-stream")
applicationOctetStream: Blob,
@contentType("application/json")
applicationJson: TestOperationId200BodyApplicationJson
}

structure TestOperationId200BodyApplicationJson {
s: String
}

@contentTypeDiscriminated
union TestOperationIdInputBody {
@contentType("application/octet-stream")
applicationOctetStream: Blob,
@contentType("application/json")
applicationJson: TestOperationIdInputBodyApplicationJson
}

structure TestOperationIdInputBodyApplicationJson {
s: String
}
```

#### Extensions

[OpenAPI extensions](https://swagger.io/docs/specification/openapi-extensions/) are preserved in the output
Smithy model through the use of the `openapiExtensions` trait.

OpenAPI:
```yaml
openapi: '3.0.'
info:
title: test
version: '1.0'
paths: {}
components:
schemas:
MyString:
type: string
x-float: 1.0
x-string: foo
x-int: 1
x-array: [1, 2, 3]
x-null: null
x-obj:
a: 1
b: 2
```

Smithy:
```smithy
use alloy.openapi#openapiExtensions

@openapiExtensions(
"x-float": 1.0,
"x-array": [1, 2, 3],
"x-string": "foo",
"x-int": 1,
"x-null": null,
"x-obj": {
a: 1,
b: 2
}
)
string MyString
```

## JSON Schema

### CLI Usage

```
> smithytranslate json-schema-to-smithy --help

Usage: smithytranslate json-schema-to-smithy --input [--input ]... [--verboseNames] [--failOnValidationErrors] [--useEnumTraitSyntax] [--outputJson]

Take Json Schema specs as input and produce Smithy files as output.

Run `smithytranslate json-schema-to-smithy --help` for all usage information.

### Differences from OpenAPI

Most of the functionality of the `OpenAPI => Smithy` conversion is the same for the `JSON Schema => Smithy` one. As such, here
we will outline any differences that exist. Everything else is the same.

#### Default Values

Default values from JSON Schema will be captured in the `smithy.api#default` trait.

JSON Schema:
```json
{
"$id": "test.json",
"$schema": "http://json-schema.org/draft-07/schema#",
"title": "Person",
"type": "object",
"properties": {
"firstName": {
"type": "string",
"default": "Sally"
}
}
}
```

Smithy:
```smithy
structure Person {
@default("Sally")
firstName: String
}
```

#### Null Values

JSON Schemas allows for declaring types such as `["string", "null"]`. This type declaration
on a required field means that the value cannot be omitted from the `JSON` payload entirely,
but may be set to `null`. For example:

JSON Schema:
```json
{
"$id": "test.json",
"$schema": "http://json-schema.org/draft-07/schema#",
"title": "Foo",
"type": "object",
"properties": {
"bar": {
"type": ["string", "null"]
}
},
"required": ["bar"]
}
```

Smithy:
```smithy
use alloy#nullable

structure Foo {
@required
@nullable
bar: String
}
```

In most protocols, there is likely no difference between an optional field and a nullable optional field.
Similarly, some protocols may not allow for required fields to be nullable. These considerations are left
up to the protocol itself.

#### Maps

JSON Schema doesn't provide a first-class type for defining maps. As such, we translate a commonly-used
convention into map types when encountered. When `patternProperties` is set to have a single entry, `.*`,
we translate that to a smithy map type.

JSON Schema:
```json
{
"$id": "test.json",
"$schema": "http://json-schema.org/draft-07/schema#",
"title": "TestMap",
"type": "object",
"patternProperties": {
".*": {
"type": "string"
}
}
}
```

Smithy:
```smithy
map TestMap {
key: String,
value: String
}
```

## Protobuf

### CLI Usage

```
> smithytranslate smithy-to-proto --help

Usage: smithytranslate smithy-to-proto --input [--input ]... [--dependency ]... [--repository ]...

Take Smithy definitions as input and produce Proto files as output.

Options and flags:
--help
Display this help text.
--input , -i
input source files
--dependency
Dependencies that contains Smithy definitions.
--repository
Specify repositories to fetch dependencies from.
```

Run `smithytranslate smithy-to-proto --help` for more usage information.

### Capabilities and Design

The design of the smithy to protobuf translation follows the semantics defined in the [alloy specification](https://github.com/disneystreaming/alloy/blob/main/docs/serialisation/protobuf.md).

### Options

Individual protobuf definitions file (`.proto`) can contain _options_. We support this feature using Smithy's metadata attribute.

There are a few importing things to notice

1. All options are defined under the metadata key `proto_options`
2. The value is an array. This is because Smithy will concatenate the arrays if the model contains multiple entries
3. Each entry of the array is an object where the keys are the namespace and the values are objects that represent the options
4. Entries for other namespaces are ignored (for example, `demo` in the example below)
5. The object that represents an option can only use `String` as value (see the example below). More detail below.

#### Stringly typed options

We used a `String` to represent the option such as `"true"` for a boolean and `"\"demo\""` for a String because it's the simplest approach to cover all use cases supported by `protoc`. `protoc` supports simple types like you'd expect: `bool`, `int`, `float` and `string`. But it also supports `identifier` which are a reference to some value that `protoc` knows about. For example: `option optimize_for = CODE_SIZE;`. Using a `String` for the value allows us to model this, while keeping thing simple. It allows prevent the users from trying to use `Array`s or `Object` as value for options.

#### Example

The following is an example:

Smithy:
```smithy
$version: "2"

metadata "proto_options" = [{
"foo": {
"java_multiple_files": "true",
"java_package": "\"foo.pkg\""
},
"demo": {
"java_multiple_files": "true"
}
}]

namespace foo

structure Foo {
value: String
}
```

Proto:
```proto
syntax = "proto3";

option java_multiple_files = true;
option java_package = "foo.pkg";

package foo;

message Foo {
string value = 1;
}
```