Test Driven Approaches to Documenting RESTful APIs

Documentation generated from source code is very popular. Solutions such as Swagger are available for many different languages and frameworks. However, limitations of annotation based tools are becoming apparent. An overwhelming number of documentation annotations make for great docs but muddy the source code. Then, something changes and the docs are out of date again.

That is where test-driven approaches come in.

Test-driven documentation solutions, such as Spring Rest Docs, generate example snippets for requests and responses from tests ensuring both code coverage and accurate documentation. It can even fail the build when documentation becomes out of date. This session will walk through how to implement test-driven documentation solutions for groovy ecosystem technologies like Spring Boot. Attendees should have a basic understanding of AsciiDoc and how to construct RESTful APIs in Spring Boot or Grails.

Transcript

1. Test-Driven Approaches
   to Documenting RESTful
   APIs
   Jenn Strater
   @jennstrater
   Groovy Users of Minnesota
   February 9, 2016
   

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2. About Me
   

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3. About Me
   • Senior Consultant at Object
   Partners, Inc.
   

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4. About Me
   • Senior Consultant at Object
   Partners, Inc.
   • Co-Founder of Gr8Ladies
   

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5. Background
   

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6. Background
   • Creating RESTful APIs with Groovy
   • Spring Boot
   • Grails
   

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7. Background
   • Creating RESTful APIs with Groovy
   • Spring Boot
   • Grails
   • Documentation
   • Swagger
   • Asciidoctor
   

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8. Current
   Documentation
   Models
   

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9. REST Maturity Model
   src: http://martinfowler.com/articles/richardsonMaturityModel.html
   

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10. REST Maturity Model
    src: http://martinfowler.com/articles/richardsonMaturityModel.html
    

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11. Endpoint Vs Resource
    Design
    

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12. Endpoint Vs Resource
    Design
    VS
    

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13. Swagger
    

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14. Swagger Approaches
    

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15. SpringFox
    src: https://www.flickr.com/photos/24874528@N04/17125924230
    

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16. Super Easy Install
    dependencies {
    compile "io.springfox:springfox-swagger2:$springfoxVersion"
    compile “io.springfox:springfox-swagger-ui:$springfoxVersion”
    }
    

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17. Custom JSON
    {

    "swagger": "2.0",

    "info": {

    "version": "1",

    "title": "My Service",

    "contact": {

    "name": "Company Name"

    },

    "license": {}

    },

    "host": "example.com",

    "basepath": "/docs",

    "tags": [

    {

    "name": "group name",

    "description": "what this group of api endpoints is for",

    }

    ],

    "paths": {

    "/api/v1/groupname/resource":

    .

    .

    .

    }
    

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18. Swagger UI
    • Springfox generated UI
    • Copy static files and
    customize
    

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19. CONSIDERATIONS
    

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20. Central Information
    Security
    Http
    Verbs
    Error
    Handling
    Http
    Status
    

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21. Multiple Services
    

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22. Headers
    src: https://cask.scotch.io/2015/06/angular-laravel-auth-10.png
    

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23. Object Mapping
    src: https://github.com/springfox/springfox/issues/281
    

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24. Versioning
    

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25. Annotation Hell
    src: http://www.nvisia.com/software-development/swagger-cataloging-with-the-worlds-most-popular-framework-for-apis
    

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26. Annotation Hell
    src: http://www.nvisia.com/software-development/swagger-cataloging-with-the-worlds-most-popular-framework-for-apis
    

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27. Advantages
    “Try-It” Button
    

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28. Swagger2Markup
    

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29. public class Swagger2MarkupTest {

    @Autowired

    private WebApplicationContext context;

    

    private MockMvc mockMvc;

    

    @Before

    public void setUp() {

    this.mockMvc = MockMvcBuilders.webAppContextSetup(this.context).build();

    }

    

    

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30. public class Swagger2MarkupTest {

    @Autowired

    private WebApplicationContext context;

    

    private MockMvc mockMvc;

    

    @Before

    public void setUp() {

    this.mockMvc = MockMvcBuilders.webAppContextSetup(this.context).build();

    }

    

    @Test

    public void convertSwaggerToAsciiDoc() throws Exception {

    this.mockMvc.perform(get("/v2/api-docs")

    .accept(MediaType.APPLICATION_JSON))

    .andDo(Swagger2MarkupResultHandler.outputDirectory(“src/docs/
    asciidoc/generated").build())

    .andExpect(status().isOk());

    }

    

    

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31. public class Swagger2MarkupTest {

    @Autowired

    private WebApplicationContext context;

    

    private MockMvc mockMvc;

    

    @Before

    public void setUp() {

    this.mockMvc = MockMvcBuilders.webAppContextSetup(this.context).build();

    }

    

    @Test

    public void convertSwaggerToAsciiDoc() throws Exception {

    this.mockMvc.perform(get("/v2/api-docs")

    .accept(MediaType.APPLICATION_JSON))

    .andDo(Swagger2MarkupResultHandler.outputDirectory(“src/docs/
    asciidoc/generated").build())

    .andExpect(status().isOk());

    }

    

    @Test

    public void convertSwaggerToMarkdown() throws Exception {

    this.mockMvc.perform(get("/v2/api-docs")

    .accept(MediaType.APPLICATION_JSON))

    .andDo(Swagger2MarkupResultHandler.outputDirectory(“src/docs/
    markdown/generated")

    .withMarkupLanguage(MarkupLanguage.MARKDOWN).build())

    .andExpect(status().isOk());

    }

    }
    

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34. Test-Driven Documentation
    Document Green
    Red Refactor
    

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35. Spring REST Docs
    

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36. Game Changers
    • Generated code snippets
    • Tests fail when documentation is missing or out-of-
    date
    • Supports Level III Rest APIs (Hypermedia)
    

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37. Getting Started
    • Documentation - Spring Projects
    • Documenting RESTful Apis - SpringOne2GX 2015 -
    Andy Wilkinson
    • Spring REST Docs - Documenting RESTful APIs
    using your tests - Devoxx Belgium 2015
    - Anders Evers
    

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38. Groovier Spring REST docs
    

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39. Groovier Spring REST docs
    • Groovy Spring Boot Project
    • Level II Rest API
    

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40. Groovier Spring REST docs
    • Groovy Spring Boot Project
    • Level II Rest API
    + Asciidoctor Gradle plugin
    

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41. Groovier Spring REST docs
    • Groovy Spring Boot Project
    • Level II Rest API
    + Asciidoctor Gradle plugin
    + MockMVC and documentation to Spock tests
    

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42. Groovy Spring Boot App
    • Start with lazybones spring boot app
    • Add mock endpoints for example
    https://github.com/jlstrater/groovy-spring-boot-
    restdocs-example
    

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43. Endpoints
    @CompileStatic

    @RestController

    @RequestMapping('/hello')

    @Slf4j

    class ExampleController {

    

    @RequestMapping(method = RequestMethod.GET, produces =
    'application/json', consumes = 'application/json')

    Example list() {

    new Example(name: 'World')

    }

    

    @RequestMapping(method = RequestMethod.POST, produces =
    'application/json', consumes = 'application/json')

    Example list(@RequestBody Example example) {

    example

    }

    }
    

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44. Asciidoctor Gradle
    Plugin
    

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45. Install
    classpath 'org.asciidoctor:asciidoctor-gradle-plugin:1.5.3'

    apply plugin: 'org.asciidoctor.convert'

    

    asciidoctor {

    sourceDir = file('src/docs')

    outputDir "$projectDir/src/main/resources/public"

    backends 'html5'

    attributes 'source-highlighter' : 'prettify',

    'imagesdir':'images',

    'toc':'left',

    'icons': 'font',

    'setanchors':'true',

    'idprefix':'',

    'idseparator':'-',

    'docinfo1':'true'

    }

    

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46. Example AsciiDoc
    = Gr8Data API Guide

    Jenn Strater;

    :doctype: book

    :icons: font

    :source-highlighter: highlightjs

    :toc: left

    :toclevels: 4

    :sectlinks:

    

    [introduction]

    = Introduction

    

    The Gr8Data API is a RESTful web service for aggregating and displaying gender
    ratios from

    various companies across the world. This document outlines how to submit data
    from your company or team and

    how to access the aggregate data.

    

    [[overview-http-verbs]]

    == HTTP verbs

    

    The Gr8Data API tries to adhere as closely as possible to standard HTTP and REST
    conventions in its

    use of HTTP verbs.
    

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47. Converted to HTML
    

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48. MockMvc Test
    src: http://www.javacodegeeks.com/2013/04/spring-mvc-introduction-in-testing.html
    

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49. Stand Alone Setup
    class ExampleControllerSpec extends Specification {

    protected MockMvc mockMvc

    

    void setup() {

    this.mockMvc = MockMvcBuilders.standaloneSetup(
    new ExampleController()).build()

    }

    

    void 'test and document get with example endpoint’() {

    when:

    ResultActions result = this.mockMvc.perform(
    get(‘/hello’).contentType(MediaType.APPLICATION_JSON))
    then:

    result
    .andExpect(status().isOk())
    .andExpect(jsonPath("name").value("World"))

    .andExpect(jsonPath("message").value("Hello, World!”))
    }
    

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50. Web Context Setup
    void setup() {

    this.mockMvc = MockMvcBuilders
    .webAppContextSetup(this.context)
    .build()

    }
    

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51. Web Context Setup
    void setup() {

    this.mockMvc = MockMvcBuilders
    .webAppContextSetup(this.context)
    .build()

    }
    If context is null,
    remember to add
    spock-spring!!
    

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52. Spring REST docs
    

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53. Gradle
    ext {

    snippetsDir = file(
    'src/docs/generated-snippets')

    }
    testCompile “org.springframework.restdocs:spring-
    restdocs-mockmvc:1.0.1.RELEASE”

    

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54. Gradle
    asciidoctor {

    dependsOn test

    sourceDir = file('src/docs')

    outputDir "$projectDir/src/main/resources/public"

    + inputs.dir snippetsDir

    backends 'html5'

    attributes 'source-highlighter' : 'prettify',

    'imagesdir':'images',

    'toc':'left',

    'icons': 'font',

    'setanchors':'true',

    'idprefix':'',

    'idseparator':'-',

    'docinfo1':'true',

    + 'snippets': snippetsDir,

    }
    

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55. Setup & GET
    

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56. Setup & GET
    class ExampleControllerSpec extends Specification {

    

    @Rule

    RestDocumentation restDocumentation = new RestDocumentation('src/docs/generated-
    snippets')

    

    protected MockMvc mockMvc

    

    void setup() {

    this.mockMvc = MockMvcBuilders.standaloneSetup(new ExampleController())

    .apply(documentationConfiguration(this.restDocumentation))

    .build()

    }
    

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57. Setup & GET
    class ExampleControllerSpec extends Specification {

    

    @Rule

    RestDocumentation restDocumentation = new RestDocumentation('src/docs/generated-
    snippets')

    

    protected MockMvc mockMvc

    

    void setup() {

    this.mockMvc = MockMvcBuilders.standaloneSetup(new ExampleController())

    .apply(documentationConfiguration(this.restDocumentation))

    .build()

    }
    

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58. Setup & GET
    class ExampleControllerSpec extends Specification {

    

    @Rule

    RestDocumentation restDocumentation = new RestDocumentation('src/docs/generated-
    snippets')

    

    protected MockMvc mockMvc

    

    void setup() {

    this.mockMvc = MockMvcBuilders.standaloneSetup(new ExampleController())

    .apply(documentationConfiguration(this.restDocumentation))

    .build()

    }
    void 'test and document get with example endpoint'() {

    when:

    ResultActions result = this.mockMvc.perform(get('/hello')

    .contentType(MediaType.APPLICATION_JSON))
    

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59. Setup & GET
    class ExampleControllerSpec extends Specification {

    

    @Rule

    RestDocumentation restDocumentation = new RestDocumentation('src/docs/generated-
    snippets')

    

    protected MockMvc mockMvc

    

    void setup() {

    this.mockMvc = MockMvcBuilders.standaloneSetup(new ExampleController())

    .apply(documentationConfiguration(this.restDocumentation))

    .build()

    }
    void 'test and document get with example endpoint'() {

    when:

    ResultActions result = this.mockMvc.perform(get('/hello')

    .contentType(MediaType.APPLICATION_JSON))
    then:

    result

    .andExpect(status().isOk())
    .andExpect(jsonPath('name').value('World'))

    .andExpect(jsonPath('message').value('Hello, World!'))

    .andDo(document('hello-get-example', preprocessResponse(prettyPrint()),

    responseFields(

    fieldWithPath('name').type(JsonFieldType.STRING).description('name'),

    fieldWithPath('message').type(JsonFieldType.STRING).description('hello world'))

    ))

    }

    }
    

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61. POST
    

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62. POST
    void 'test and document post with example endpoint and custom name'() {

    when:
    ResultActions result = this.mockMvc.perform(post(‘/hello')
    .content(new ObjectMapper()
    .writeValueAsString(new Example(name: 'mockmvc test’))
    .contentType(MediaType.APPLICATION_JSON))
    

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63. POST
    void 'test and document post with example endpoint and custom name'() {

    when:
    ResultActions result = this.mockMvc.perform(post(‘/hello')
    .content(new ObjectMapper()
    .writeValueAsString(new Example(name: 'mockmvc test’))
    .contentType(MediaType.APPLICATION_JSON))
    then:

    result

    .andExpect(status().isOk())

    .andExpect(jsonPath('name').value('mockmvc test'))

    .andExpect(jsonPath('message').value('Hello, mockmvc test!'))
    .andDo(document('hello-post-example',
    preprocessResponse(prettyPrint()),

    responseFields(

    fieldWithPath('name').type(JsonFieldType.STRING)

    .description('name'),

    fieldWithPath('message').type(JsonFieldType.STRING)

    .description('hello world'))

    ))

    }
    

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65. List Example
    void 'test and document get of a list from example endpoint'() {

    when:

    ResultActions result = this.mockMvc.perform(get('/hello/list')

    .contentType(MediaType.APPLICATION_JSON))

    

    then:

    result

    .andExpect(status().isOk())

    .andDo(document('hello-list-example',
    preprocessResponse(prettyPrint()),

    responseFields(

    fieldWithPath('[].message').type(JsonFieldType.STRING)

    .description('message'))

    ))

    }
    

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66. List Example
    void 'test and document get of a list from example endpoint'() {

    when:

    ResultActions result = this.mockMvc.perform(get('/hello/list')

    .contentType(MediaType.APPLICATION_JSON))

    

    then:

    result

    .andExpect(status().isOk())

    .andDo(document('hello-list-example',
    preprocessResponse(prettyPrint()),

    responseFields(

    fieldWithPath('[].message').type(JsonFieldType.STRING)

    .description('message'))

    ))

    }
    

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67. Central Info - Errors
    void 'test and document error format’() {
    when:

    ResultActions result = this.mockMvc.perform(put('/error')

    .contentType(MediaType.APPLICATION_JSON)

    .requestAttr(RequestDispatcher.ERROR_STATUS_CODE, 405)

    .requestAttr(RequestDispatcher.ERROR_REQUEST_URI, '/hello')

    .requestAttr(RequestDispatcher.ERROR_MESSAGE,
    "Request method 'PUT' not supported"))

    

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68. Central Info - Errors
    void 'test and document error format’() {
    when:

    ResultActions result = this.mockMvc.perform(put('/error')

    .contentType(MediaType.APPLICATION_JSON)

    .requestAttr(RequestDispatcher.ERROR_STATUS_CODE, 405)

    .requestAttr(RequestDispatcher.ERROR_REQUEST_URI, '/hello')

    .requestAttr(RequestDispatcher.ERROR_MESSAGE,
    "Request method 'PUT' not supported"))

    then:

    result
    .andExpect(status().isMethodNotAllowed())

    .andDo(document('error-example', preprocessResponse(prettyPrint()),

    responseFields(

    fieldWithPath(‘error')
    .description('The HTTP error that occurred, e.g. `Bad Request`'),

    fieldWithPath(‘message')
    .description('A description of the cause of the error'),

    fieldWithPath('path').description('The path to which the request was made'),

    fieldWithPath('status').description('The HTTP status code, e.g. `400`'),

    fieldWithPath(‘timestamp')
    .description('The time, in milliseconds, at which the error occurred'))

    ))

    }
    

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69. Failing Tests
    

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70. Failing Tests
    

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71. Generated Snippets
    • curl-request.adoc
    • http-request.adoc
    • http-response.adoc
    • response-fields.adoc
    • request-parameters.adoc
    

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72. Add Snippets to AsciiDoc
    == Errors

    

    Whenever an error response (status code >= 400) is returned, the
    body will contain a JSON object

    that describes the problem. The error object has the following
    structure:

    

    include::{snippets}/error-example/response-fields.adoc[]

    

    For example, a request that attempts to apply a non-existent tag
    to a note will produce a

    `400 Bad Request` response:

    

    include::{snippets}/error-example/http-response.adoc[]

    

    [[resources]]

    = Resources

    

    include::resources/example.adoc[]
    

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73. Build Docs
    src/docs
    index.adoc
    src/main/
    resources/public/
    html5
    index.html
    

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74. Publish Docs
    publish.gradle
    buildscript {

    repositories {

    jcenter()

    }

    

    dependencies {

    classpath 'org.ajoberstar:gradle-git:1.1.0'

    }

    }

    

    apply plugin: 'org.ajoberstar.github-pages'

    

    githubPages {

    repoUri = 'git@github.com:jlstrater/groovy-spring-boot-restdocs-example.git'

    pages {

    from(file('build/docs'))

    }

    }
    

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75. http://jlstrater.github.io/groovy-spring-boot-restdocs-example
    

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76. Grails
    Rest Assured - 1.1.0 Release
    img src: https://www.flickr.com/photos/dskley/15558668690
    

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77. Conclusion
    • API documentation is complex
    • Choosing the right tool for the job not just about the
    easiest one to setup
    • Spring REST Docs is a promising tool to enforce
    good testing and documentation practices without
    muddying source code.
    

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78. Questions?
    https://github.com/jlstrater/groovy-spring-boot-restdocs-example
    @jennstrater
    

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79. Questions?
    https://github.com/jlstrater/groovy-spring-boot-restdocs-example
    @jennstrater
    

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