Execution failed for task ':app:mergeExtDexDebug'.
Getting this error while building.

Execution failed for task ':app:mergeExtDexDebug'.
> Could not resolve all files for configuration ':app:debugRuntimeClasspath'.
   > Failed to transform artifact 'iconics-core.aar (com.mikepenz:iconics-core:3.2.5)' to match attributes {artifactType=android-dex, dexing-is-debuggable=true, dexing-min-sdk=21}
      > Execution failed for DexingTransform: /Users/apple/.gradle/caches/transforms-2/files-2.1/d5a9e46b08fc3a87a4eb4c070e854658/jars/classes.jar.
         > Error while dexing.