Проблема с зависимостями плагина iOS Flutter

Я пытаюсь разработать плагин Flutter для Tapkey Mobile SDK.

Мне удалось добавить их SDK, изменив podspec плагина и подфайл примера:

tapkey.podspec:

Pod::Spec.new do |s|
  s.name             = 'tapkey'
  s.version          = '0.0.1'
  s.summary          = 'A tapkey flutter plugin'
  s.description      = <<-DESC
A tapkey flutter plugin
                       DESC
  s.homepage         = 'http://example.com'
  s.license          = { :file => '../LICENSE' }
  s.author           = { 'Your Company' => '[email protected]' }
  s.source           = { :path => '.' }
  s.source_files = 'Classes/**/*'
  s.dependency 'Flutter'
  s.platform = :ios, '9.0'

  s.dependency 'TapkeyMobileLib', '~> 2.5.10.0'
  s.static_framework = true

  # Flutter.framework does not contain a i386 slice. Only x86_64 simulators are supported.
  s.pod_target_xcconfig = { 'DEFINES_MODULE' => 'YES', 'VALID_ARCHS[sdk=iphonesimulator*]' => 'x86_64' }
  s.swift_version = '5.0'
end

Подфайл:

platform :ios, '9.0'

source 'https://github.com/tapkey/TapkeyCocoaPods'
source 'https://github.com/CocoaPods/Specs.git'

# unmodified Podfile

Однако создание приложения завершается с ошибкой:

Running Xcode build...
Xcode build done.                                           26,4s
Failed to build iOS app
Error output from Xcode build:
    2019-12-26 22:07:57.289 xcodebuild[57331:4745526]  DTDeviceKit: deviceType from 1816565999a8254de93745cb449376c7b2946e65 was NULL
    2019-12-26 22:07:57.441 xcodebuild[57331:4745803]  DTDeviceKit: deviceType from 1816565999a8254de93745cb449376c7b2946e65 was NULL
    ** BUILD FAILED **

Xcode's output:
    22 warnings generated.
    <module-includes>:1:9: note: in file included from <module-includes>:1:
    #import "Headers/GsonPublicHeader.h"
            ^
    /Users/zarbex/IdeaProjects/tapkey/example/ios/Pods/GsonJ2ObjC-Light/Gson.framework/Headers/GsonPublicHeader.h:1:10: note: in file included from /Users/zarbex/IdeaProjects/tapkey/example/ios/Pods/GsonJ2ObjC-Light/Gson.framework/Headers/GsonPublicHeader.h:1:
    #include "$Gson$Preconditions.h"
             ^
    /Users/zarbex/IdeaProjects/tapkey/example/ios/Pods/GsonJ2ObjC-Light/Gson.framework/Headers/$Gson$Preconditions.h:6:10: error: 'J2ObjC_header.h' file not found
    #include "J2ObjC_header.h"
             ^
    <unknown>:0: error: could not build Objective-C module 'Gson'
    <module-includes>:1:9: note: in file included from <module-includes>:1:
    #import "Headers/TapkeyMobileLib.h"
            ^
    /Users/zarbex/IdeaProjects/tapkey/example/ios/Pods/TapkeyMobileLib/TapkeyMobileLib.framework/Headers/TapkeyMobileLib.h:27:9: note: in file included from /Users/zarbex/IdeaProjects/tapkey/example/ios/Pods/TapkeyMobileLib/TapkeyMobileLib.framework/Headers/TapkeyMobileLib.h:27:
    #import "CipherFactories.h"
            ^
    note: Using new build system
    note: Planning build
    note: Constructing build description

Could not build the precompiled application for the device.

Я просмотрел несколько похожих проблем с GitHub, но не смог решить проблему.