question: private void decrementCopyFieldTargetCount ( SchemaField dest ) { Integer count = copyFieldTargetCounts . get ( dest ) ; assert count != null ; if ( count <= 1 ) { copyFieldTargetCounts . remove ( dest ) ; } else { copyFieldTargetCounts . put ( dest , count - 1 ) ; } }
target:  Decrements the count for the given destination field in copyFieldTargetCounts.