Journey of Feature Flag development in LINE Android

GDG DevFest Tokyo 2019 での講演資料です
https://tokyo.gdgjapan.org/devfest2019

Transcript

1. Journey of Feature Flag
   development in LINE Android
   > Hidetsugu Tamaki / LINE Corporation
   

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2. > LINE Android Development
   Hidetsugu Tamaki (@r_ralph_h)
   Introduction
   > Apr. 2018 ~
   > LINE Corporation / Software Engineer
   

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3. Agenda > Pain Points of Feature Branches
   > Benefits of Feature Flags
   > History of Feature Flags in LINE Android
   

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4. Agenda > Pain Points of Feature Branches
   > Benefits of Feature Flags
   > History of Feature Flags in LINE Android
   

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5. Feature Branch
   Main branch
   

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6. Feature Branch
   Main branch
   Feature branch
   

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7. Feature Branch
   Main branch
   Feature branch
   Pull requests
   

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8. Feature Branch
   Main branch
   Feature branch
   Pull requests
   

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9. LINE Android Project
   Developers
   100
   Changes per week in LoC
   20,000
   

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10. Feature Branches in Large Applications
    Main branch
    Feature branches
    

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11. Agenda > Pain Points of Feature Branches
    > Benefits of Feature Flags
    > History of Feature Flag in LINE Android
    

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12. Feature Flag Strategy
    Main branch
    Sticker feature PRs
    

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13. Feature Flag Strategy
    Main branch
    
    Sticker feature PRs
    

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14. Feature Flag Strategy
    Main branch
    
    Sticker feature PRs
    

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15. Feature Flag Usage
    > View visibility
    . .. .
    
    

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16. Feature Flag Usage
    > Activity
    , ,
    =
    ( ) :
    =
    ( .) :
    > View visibility
    , ,
    

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17. Feature Flags Achieve
    > Conflict minimization
    > Smoother release schedule management
    > Instant toggling
    > Better collaboration with stakeholders
    

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18. Feature Flags Achieve
    > Conflict minimization
    > Smoother release schedule management
    > Instant toggling
    > Better collaboration with stakeholders
    

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19. Conflict Minimization
    Main branch
    Sticker feature PRs
    

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20. Conflict Minimization
    Main branch
    Sticker feature PRs
    Theme feature PRs
    

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21. Conflict Minimization
    Main branch
    Sticker feature PRs
    Theme feature PRs
    Saved PRs Saved PRs
    

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22. Conflict Minimization
    Main branch
    Sticker feature PRs
    Theme feature PRs
    Conflict
    Saved PRs Saved PRs
    

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23. Feature Flags Achieve
    > Conflict minimization
    > Smoother release schedule management
    > Instant toggling
    > Better collaboration with stakeholders
    

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24. Feature Flags Achieve
    > Conflict minimization
    > Smoother release schedule management
    > Instant toggling
    > Better collaboration with stakeholders
    

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25. Smoother Release Schedule Management
    Main branch
    Sticker feature PRs
    

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26. Smoother Release Schedule Management
    Main branch
    Release branches 1.0
    Sticker feature PRs
    

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27. Smoother Release Schedule Management
    Main branch
    Release branches 1.0
    
    
    Sticker feature PRs
    

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28. Smoother Release Schedule Management
    Main branch
    Release branches 1.0 2.0
    Sticker feature PRs
    
    
    
    
    

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29. Feature Flags Achieve
    > Conflict minimization
    > Smoother release schedule management
    > Instant toggling
    > Better collaboration with stakeholders
    

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30. Feature Flags Achieve
    > Conflict minimization
    > Smoother release schedule management
    > Instant toggling
    > Better collaboration with stakeholders
    

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31. Instant Toggling
    Main branch
    Release branch 1.0
    
    Sticker feature PR
    

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32. Sticker feature PR
    ✗
    Instant Toggling
    Main branch
    Release branch 1.0
    Critical issue
    
    

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33. Instant Toggling
    Main branch
    Release branch 1.0
    Critical issue
    Sticker feature PR Conflicting PR
    ✗
    
    

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34. ✗
    Instant Toggling
    Main branch
    Release branch 1.0
    Critical issue
    Conflicting PR
    Sticker feature PR
    
    

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35. Feature Flags Achieve
    > Conflict minimization
    > Smoother release schedule management
    > Instant toggling
    > Better collaboration with stakeholders
    

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36. Feature Flags Achieve
    > Conflict minimization
    > Smoother release schedule management
    > Instant toggling
    > Better collaboration with stakeholders
    

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37. Better Collaboration with Stakeholders
    Developer Planner
    Tester
    Designer
    
    
    Organization
    

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38. Better Collaboration with Stakeholders
    Developer Planner
    Tester
    Designer
    Users
    Partners
    
    
    Organization
    
    
    

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39. Feature Flags Achieve
    > Conflict minimization
    > Smoother release schedule management
    > Instant toggling
    > Better collaboration with stakeholders
    

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40. Feature Flags Achieve
    > Conflict minimization
    > Smoother release schedule management
    > Instant toggling
    > Better collaboration with stakeholders
    

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41. Limitation of Feature Flags
    Not a “silver bullet”
    > Difficult to apply
    > Updating libraries
    > Overkill
    > Prototyping
    

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42. Reference
    ./ 1 1
    Presented at DroidKaigi 2019
    https://speakerdeck.com/line_developers/flag-based-feature-management
    

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43. Agenda > Pain Points of Feature Branches
    > Benefits of Feature Flags
    > History of Feature Flags in LINE Android
    

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44. Feature Flags in LINE Android
    > Started with a simple Gradle script (Dec. 2015)
    > Injects values into BuildConfig file
    > Loads values from a property file
    

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45. Feature Flags in LINE Android
    > Started with a simple Gradle script (Dec. 2015)
    > Injects values into BuildConfig file
    = = =
    # . "
    = = =
    # . "
    > Loads values from a property file
    

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46. Feature Flags in LINE Android
    > Started with a simple Gradle script (Dec. 2015)
    > Injects values into BuildConfig file
    
    
    > Loads values from a property file
    

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47. > Toggle flag by user name or app version
    > Toggle flag at runtime
    > Support Gradle submodule
    Growth of Feature Flags
    

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48. > Toggle flag by user name or app version
    > Toggle flag at runtime
    > Support Gradle submodule
    Growth of Feature Flags
    

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49. Module Structure of LINE Android
    line-android-app submodule-sticker
    Product Flavor Product Flavor
    
    

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50. Module Structure of LINE Android
    line-android-app submodule-sticker
    Product Flavor Product Flavor
    
    dev, beta, rc, release debug, release
    

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51. Initial Feature Flags Implementation
    line-android-app
    FeatureFlag script
    Flag Property File
    Product Flavor
    Refers to
    Product Flavor
    submodule-sticker
    
    

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52. Initial Feature Flags Implementation
    line-android-app
    FeatureFlag script
    Flag Property File
    Product Flavor
    BuildConfig.java
    Injects values into
    Product Flavor
    submodule-sticker
    Refers to
    
    

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53. Misused Feature Flags in Submodules
    line-android-app
    FeatureFlag script
    Flag Property File
    Product Flavor
    BuildConfig.java
    FeatureFlag script
    Product Flavor
    BuildConfig.java
    submodule-sticker
    Refers to
    Injects values into
    Refers to
    Injects values into
    
    

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54. Misused Feature Flags in Submodules
    line-android-app
    FeatureFlag script
    Flag Property File
    Product Flavor
    BuildConfig.java
    FeatureFlag script
    Product Flavor
    BuildConfig.java
    submodule-sticker
    Back reference
    
    Refers to
    Injects values into
    Refers to
    Injects values into
    

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55. Misused Feature Flags in Submodules
    line-android-app
    FeatureFlag script
    Flag Property File
    Product Flavor
    BuildConfig.java
    FeatureFlag script
    Product Flavor
    BuildConfig.java
    dev, beta, rc, release debug, release
    submodule-sticker
    Back reference
    
    Refers to
    Injects values into
    Refers to
    Injects values into
    

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56. Misused Feature Flags in Submodules
    line-android-app
    FeatureFlag script
    Flag Property File
    Product Flavor
    BuildConfig.java
    FeatureFlag script
    Product Flavor
    BuildConfig.java
    package com.linecorp.line package com.linecorp.sticker
    dev, beta, rc, release debug, release
    submodule-sticker
    Back reference
    
    Refers to
    Injects values into
    Refers to
    Injects values into
    

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57. Problems of Misuse
    > Caused by BuildConfig.java and product flavors
    > Generated wrong values
    > Caused by back reference
    > Submodules were no longer standalone
    

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58. Problems of Misuse
    > Caused by BuildConfig.java and product flavors
    > Generated wrong values
    > Caused by back reference
    > Submodules were no longer standalone
    

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59. Workaround for Wrong Flag Values
    Simplified references by extracting Feature Flags into a module
    

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60. Workaround for Wrong Flag Values
    line-android-app
    FeatureFlag script
    Flag Property File
    Product Flavor
    BuildConfig.java
    FeatureFlag script
    Product Flavor
    BuildConfig.java
    submodule-sticker
    Back reference
    
    Refers to
    Injects values into
    Refers to
    Injects values into
    

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61. Workaround for Wrong Flag Values
    line-android-app
    FeatureFlag script
    Flag Property File
    Product Flavor
    BuildConfig.java
    FeatureFlag script
    feature-flag
    BuildConfig.java
    Refers to
    submodule-sticker
    
    Refers to
    Injects values into
    Injects values into
    

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62. Workaround for Wrong Flag Values
    BuildConfig.java
    BuildConfig.java
    Injects values into
    Injects values into
    package com.linecorp.line
    package com.linecorp.sticker
    

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63. Workaround for Wrong Flag Values
    FeatureFlag.java
    FeatureFlag.java
    Creates
    Creates
    package com.linecorp.line
    package com.linecorp.line
    

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64. Workaround for Wrong Flag Values
    line-android-app
    FeatureFlag script
    Flag Property File
    Product Flavor
    FeatureFlag.java
    FeatureFlag script
    feature-flag
    FeatureFlag.java
    Refers to
    submodule-sticker
    
    Refers to
    Creates
    Creates
    

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65. 
    
    Workaround for Wrong Flag Values
    line-android-app
    FeatureFlag script
    Flag Property File
    Product Flavor
    FeatureFlag.java
    FeatureFlag script
    feature-flag
    FeatureFlag.java
    Refers to
    submodule-sticker
    
    
    Refers to
    Creates
    Creates
    

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66. Workaround for Wrong Flag Values
    line-android-app
    FeatureFlag script
    Flag Property File
    Product Flavor
    FeatureFlag.java
    submodule-sticker
    
    Refers to
    Creates
    

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67. Things Got Worse
    > Tricky usage of `
    
    > Wrong dependencies still remain
    > Poor compatibility with automated testing
    

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68. Things Got Worse
    > Tricky usage of `
    
    > Wrong dependencies still remain
    > Poor compatibility with automated testing
    

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69. Things Got Worse
    > Tricky usage of `
    
    > Wrong dependencies still remain
    > Poor compatibility with automated testing
    

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70. Things Got Worse
    > Tricky usage of `
    
    > Wrong dependencies still remain
    > Poor compatibility with automated testing
    

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71. Things Got Worse
    > Tricky usage of `
    
    > Wrong dependencies still remain
    > Poor compatibility with automated testing
    

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72. Proper Solution
    Isolated dependencies by processing flags within modules
    

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73. Proper Solution
    line-android-app
    FeatureFlag script
    Flag Property File
    Product Flavor
    FeatureFlag.java
    submodule-sticker
    
    Refers to
    Creates
    

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74. Proper Solution
    line-android-app
    FeatureFlag script
    Flag Property File
    Product Flavor
    FeatureFlag.java
    submodule-sticker
    
    Refers to
    FeatureFlag script
    Flag Property File
    Product Flavor
    FeatureFlag.java
    Refers to
    Creates Creates
    

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75. Flag Property File
    Product Flavor
    Proper Solution
    debug, release
    

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76. FeatureFlag.java FeatureFlag.java
    Proper Solution
    package com.linecorp.line package com.linecorp.sticker
    

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77. Proper Solution
    line-android-app
    FeatureFlag script
    Flag Property File
    Product Flavor
    FeatureFlag.java
    submodule-sticker
    
    Refers to
    FeatureFlag script
    Flag Property File
    Product Flavor
    FeatureFlag.java
    Refers to
    Links to
    Creates Creates
    

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78. Proper Solution
    line-android-app
    FeatureFlag script
    Flag Property File
    Product Flavor
    FeatureFlag.java
    submodule-sticker
    
    Refers to
    FeatureFlag script
    Flag Property File
    Product Flavor
    FeatureFlag.java
    Refers to
    Links to
    Refers to
    Creates Creates
    

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79. Link to Submodule Flag Values
    &,
    A = A
    :
    
    
    
    &, -
    line-android-app
    submodule-sticker
    

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80. )(& ,( - (,
    = =
    :
    
    
    
    )(& ,( - (,
    = =
    :
    
    
    
    Property Parsing: Format
    > Written with “disjunctive normal form” style property
    

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81. Property Parsing: Phase
    > Enabled if build variant is
    Phase
    Phase
    > Enabled if build variant is
    
    

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82. Property Parsing: Value Calculation
    variant
    ( - -)&
    :
    =
    
    
    
    ( - -)& :
    =
    
    
    
    ( - -)&
    Optimization
    Phase resolution
    

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83. ( - -)&
    :
    =
    
    
    
    Property Parsing: Value Calculation
    variant
    Optimization
    Phase resolution
    ( - -)& :
    =
    
    
    
    ( - -)&
    

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84. Property Parsing: Value Calculation
    ( - -)&
    :
    =
    
    
    
    variant
    Optimization
    Phase resolution
    ( - -)& :
    =
    
    
    
    ( - -)&
    

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85. Property Parsing: Value Calculation
    variant
    ( - -)&
    :
    =
    
    
    
    ( - -)& :
    =
    
    
    
    ( - -)&
    Optimization
    Phase resolution
    

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86. E F variant
    Property Parsing: Value Calculation
    )& ) ) () II )-)& ) F AC:
    F E )& ) ) .-& )
    )& ) ) F II E F AC:
    F E )& ) ) .-& )
    )& ) ) F AC: F E )& ) )
    Optimization
    Variant resolution
    Package name extraction
    )& ) ) CA CED F E E =
    
    
    )& ) ) II
    F AC:
    F E
    
    
    
    )& ) ) II F AC:
    F E
    
    
    
    )& ) ) F AC: F E
    
    
    
    Optimization
    Phase resolution
    

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87. Property Parsing: Value Calculation
    E F variant
    )& ) ) () II )-)& ) F AC:
    F E )& ) ) .-& )
    )& ) ) F II E F AC:
    F E )& ) ) .-& )
    )& ) ) F AC: F E )& ) )
    Optimization
    Variant resolution
    Package name extraction
    )& ) ) CA CED F E E =
    
    
    )& ) ) II
    F AC:
    F E
    
    
    
    )& ) ) II F AC:
    F E
    
    
    
    )& ) ) F AC: F E
    
    
    
    Optimization
    Phase resolution
    

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88. Property Parsing: Value Calculation
    E F variant
    )& ) ) () II )-)& ) F AC:
    F E )& ) ) .-& )
    )& ) ) F II E F AC:
    F E )& ) ) .-& )
    )& ) ) F AC: F E )& ) )
    Optimization
    Variant resolution
    Package name extraction
    )& ) ) CA CED F E E =
    
    
    )& ) ) II
    F AC:
    F E
    
    
    
    )& ) ) II F AC:
    F E
    
    
    
    )& ) ) F AC: F E
    
    
    
    Optimization
    Phase resolution
    

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89. Property Parsing: Value Calculation
    E F variant
    )& ) ) () II )-)& ) F AC:
    F E )& ) ) .-& )
    )& ) ) F II E F AC:
    F E )& ) ) .-& )
    )& ) ) F AC: F E )& ) )
    Optimization
    Variant resolution
    Package name extraction
    )& ) ) CA CED F E E =
    
    
    )& ) ) II
    F AC:
    F E
    
    
    
    )& ) ) II F AC:
    F E
    
    
    
    )& ) ) F AC: F E
    
    
    
    Optimization
    Phase resolution
    

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90. Property Parsing: Value Calculation
    E F variant
    )& ) ) () II )-)& ) F AC:
    F E )& ) ) .-& )
    )& ) ) F II E F AC:
    F E )& ) ) .-& )
    )& ) ) F AC: F E )& ) )
    Optimization
    Variant resolution
    Package name extraction
    )& ) ) CA CED F E E =
    
    
    )& ) ) II
    F AC:
    F E
    
    
    
    )& ) ) II F AC:
    F E
    
    
    
    )& ) ) F AC: F E
    
    
    
    Optimization
    Phase resolution
    

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91. Results
    > Gradle plugin instead of script
    > Simplified dependencies
    > Correct feature flag values in submodules
    

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92. Results
    > Gradle plugin instead of script
    > Simplified dependencies
    > Correct feature flag values in submodules
    

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93. Results
    > Gradle plugin instead of script
    > Simplified dependencies
    > Correct feature flag values in submodules
    

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94. Results
    > Gradle plugin instead of script
    > Simplified dependencies
    > Correct feature flag values in submodules
    

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95. Available Now
    > https://github.com/line/feature-flag-android
    

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96. Summary
    > Solved pain points of feature branches with feature flags
    > Gradle plugin for Android is now available
    

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97. Thank You
    

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