Support of gradle 1.12. Why classifier has become mandatory?

* What went wrong:
Execution failed for task ':com.tojc.common:publishReleaseArtifactPublicationToMavenRepository'.
> Failed to publish publication 'releaseArtifact' to repository 'maven'
   > Invalid publication 'releaseArtifact': Cannot determine main artifact - multiple artifacts found with empty classifier.