참조하는 라이브러리의 개수가 65536개 메서드를 초과하면 발생하는 에러이다. FAILURE: Build failed with an exception. * What went wrong: Execution failed for task ':app:mergeExtDexDebug'. > A failure occurred while executing com.android.build.gradle.internal.tasks.DexMergingTaskDelegate > There was a failure while executing work items > A failure occurred while executing com.android.build.gradle.internal.tasks.DexMergingWorkAct..