ArrayList cannot be cast to class String in VariantContextConverter

[heuermh]

$ adam-submit transformVariants NA12878.hg38.g.vcf.gz NA12878.hg38.variants.parquet
...
Caused by: java.lang.ClassCastException: class java.util.ArrayList cannot be cast to class java.lang.String (java.util.ArrayList and java.lang.String are in module java.base of loader 'bootstrap')
	at org.bdgenomics.adam.converters.VariantContextConverter.asString(VariantContextConverter.scala:1350)
	at org.bdgenomics.adam.converters.VariantContextConverter.$anonfun$lineToVariantContextExtractor$17(VariantContextConverter.scala:1512)
	at scala.Option.map(Option.scala:230)
	at org.bdgenomics.adam.converters.VariantContextConverter.variantContextFieldExtractor(VariantContextConverter.scala:1469)
	at org.bdgenomics.adam.converters.VariantContextConverter.$anonfun$lineToVariantContextExtractor$16(VariantContextConverter.scala:1512)
	at org.bdgenomics.adam.converters.VariantContextConverter.$anonfun$lineToVariantContextExtractor$16$adapted(VariantContextConverter.scala:1510)
	at org.bdgenomics.adam.converters.VariantContextConverter.$anonfun$makeVariantFormatFn$13(VariantContextConverter.scala:1774)
	at scala.collection.TraversableLike.$anonfun$flatMap$1(TraversableLike.scala:293)
	at scala.collection.mutable.ResizableArray.foreach(ResizableArray.scala:62)
	at scala.collection.mutable.ResizableArray.foreach$(ResizableArray.scala:55)
	at scala.collection.mutable.ArrayBuffer.foreach(ArrayBuffer.scala:49)
	at scala.collection.TraversableLike.flatMap(TraversableLike.scala:293)
	at scala.collection.TraversableLike.flatMap$(TraversableLike.scala:290)
	at scala.collection.AbstractTraversable.flatMap(Traversable.scala:108)
	at org.bdgenomics.adam.converters.VariantContextConverter.convert$1(VariantContextConverter.scala:1774)