Spark - Compare schemas, ignoring ``nullable`` settting

SimilarSchema.scala

package object spark {
  import org.apache.spark.sql.types.StructType

  implicit class StructTypeExtension(schema: StructType) {
    import org.apache.spark.sql.types.StructField 

    implicit def similar(other: StructType): Boolean = _similar(schema, other)
    implicit val fieldOrdering: Ordering[StructField] = Ordering.by(field => field.name)
 
    private final def _similar(_this: StructType, _other: StructType): Boolean =
      if(_this.fields.size != _other.fields.size) false
      else
        (_this.fields.sorted zip _other.fields.sorted)
          .forall { case (t, o) => _similar(t, o) }

    private final def _similar(_this: StructField, _other: StructField): Boolean =
      if((_this.dataType.typeName == "struct") && (_other.dataType.typeName == "struct"))
        _similar(_this.dataType.asInstanceOf[StructType], _other.dataType.asInstanceOf[StructType])
      else
        (_this.name == _other.name) && (_this.dataType == _other.dataType) //-- comparison
  }
}