Add flag to enable compatibility with non-hierarchical projects (#1118)

Author: oldergod

gradle.properties

@@ -9,6 +9,10 @@ kotlin.mpp.stability.nowarn=true
 # https://issues.sonatype.org/browse/NEXUS-21802
 systemProp.org.gradle.internal.publish.checksums.insecure=true
 
+# Enable compatibility with non-hierarchical projects.
+# See https://kotlinlang.org/docs/multiplatform-hierarchy.html#for-library-authors
+kotlin.mpp.enableCompatibilityMetadataVariant=true
+
 GROUP=com.squareup.okio
 VERSION_NAME=3.1.0
 kotlin.mpp.commonizerLogLevel=info