[Error] Execution failed for task ':app:checkDebugDuplicateClasses'.

플러터를 업그레이드 하면서 안드로이드 시뮬레이터를 실행하려는데, 갑자기 처음 보는 에러가 발생했다...

아직은 해결 못하는 점... 에러가 2가지 인데, 클래스가 중복되는 이슈와 gradle 버전이 프로젝트와 맞지 않다는 이슈이다. 

해결을 하고 해결방법을 작성해보도록 하겠다.

FAILURE: Build completed with 2 failures.

1: Task failed with an exception.
-----------
* What went wrong:
Execution failed for task ':app:checkDebugDuplicateClasses'.
> A failure occurred while executing com.android.build.gradle.internal.tasks.CheckDuplicatesRunnable
   > Duplicate class kotlin.collections.jdk8.CollectionsJDK8Kt found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk8-1.6.0 (org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.6.0)
     Duplicate class kotlin.internal.jdk7.JDK7PlatformImplementations found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk7-1.7.21 (org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.7.21)
     Duplicate class kotlin.internal.jdk7.JDK7PlatformImplementations$ReflectSdkVersion found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk7-1.7.21 (org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.7.21)
     Duplicate class kotlin.internal.jdk8.JDK8PlatformImplementations found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk8-1.6.0 (org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.6.0)
     Duplicate class kotlin.io.path.DirectoryEntriesReader found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk7-1.7.21 (org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.7.21)
     Duplicate class kotlin.io.path.ExperimentalPathApi found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk7-1.7.21 (org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.7.21)
     Duplicate class kotlin.io.path.FileVisitorBuilder found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk7-1.7.21 (org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.7.21)
     Duplicate class kotlin.io.path.FileVisitorBuilderImpl found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk7-1.7.21 (org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.7.21)
     Duplicate class kotlin.io.path.FileVisitorImpl found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk7-1.7.21 (org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.7.21)
     Duplicate class kotlin.io.path.LinkFollowing found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk7-1.7.21 (org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.7.21)
     Duplicate class kotlin.io.path.PathNode found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk7-1.7.21 (org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.7.21)
     Duplicate class kotlin.io.path.PathRelativizer found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk7-1.7.21 (org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.7.21)
     Duplicate class kotlin.io.path.PathTreeWalk found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk7-1.7.21 (org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.7.21)
     Duplicate class kotlin.io.path.PathTreeWalk$bfsIterator$1 found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk7-1.7.21 (org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.7.21)
     Duplicate class kotlin.io.path.PathTreeWalk$dfsIterator$1 found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk7-1.7.21 (org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.7.21)
     Duplicate class kotlin.io.path.PathTreeWalkKt found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk7-1.7.21 (org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.7.21)
     Duplicate class kotlin.io.path.PathWalkOption found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk7-1.7.21 (org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.7.21)
     Duplicate class kotlin.io.path.PathsKt found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk7-1.7.21 (org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.7.21)
     Duplicate class kotlin.io.path.PathsKt__PathReadWriteKt found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk7-1.7.21 (org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.7.21)
     Duplicate class kotlin.io.path.PathsKt__PathUtilsKt found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk7-1.7.21 (org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.7.21)
     Duplicate class kotlin.jdk7.AutoCloseableKt found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk7-1.7.21 (org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.7.21)
     Duplicate class kotlin.jvm.jdk8.JvmRepeatableKt found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk8-1.6.0 (org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.6.0)
     Duplicate class kotlin.random.jdk8.PlatformThreadLocalRandom found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk8-1.6.0 (org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.6.0)
     Duplicate class kotlin.streams.jdk8.StreamsKt found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk8-1.6.0 (org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.6.0)
     Duplicate class kotlin.streams.jdk8.StreamsKt$asSequence$$inlined$Sequence$1 found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk8-1.6.0 (org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.6.0)
     Duplicate class kotlin.streams.jdk8.StreamsKt$asSequence$$inlined$Sequence$2 found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk8-1.6.0 (org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.6.0)
     Duplicate class kotlin.streams.jdk8.StreamsKt$asSequence$$inlined$Sequence$3 found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk8-1.6.0 (org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.6.0)
     Duplicate class kotlin.streams.jdk8.StreamsKt$asSequence$$inlined$Sequence$4 found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk8-1.6.0 (org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.6.0)
     Duplicate class kotlin.text.jdk8.RegexExtensionsJDK8Kt found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk8-1.6.0 (org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.6.0)
     Duplicate class kotlin.time.jdk8.DurationConversionsJDK8Kt found in modules jetified-kotlin-stdlib-1.8.0 (org.jetbrains.kotlin:kotlin-stdlib:1.8.0) and jetified-kotlin-stdlib-jdk8-1.6.0 (org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.6.0)

     Go to the documentation to learn how to <a href="d.android.com/r/tools/classpath-sync-errors">Fix dependency resolution errors</a>.

* Try:
> Run with --stacktrace option to get the stack trace.
> Run with --info or --debug option to get more log output.
> Run with --scan to get full insights.
==============================================================================

2: Task failed with an exception.
-----------
* What went wrong:
java.lang.StackOverflowError (no error message)

* Try:
> Run with --stacktrace option to get the stack trace.
> Run with --info or --debug option to get more log output.
> Run with --scan to get full insights.
==============================================================================

* Get more help at https://help.gradle.org

BUILD FAILED in 6s
Exception: Gradle task assembleDebug failed with exit code 1