<?xml version="1.0"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">

<xs:element name="note">
  <xs:complexType>
    <xs:sequence>
      <xs:element ref="to"/>
      <xs:element ref="from"/>
      <xs:element ref="heading"/>
      <xs:element ref="body"/>
    </xs:sequence>
  </xs:complexType>
</xs:element>

<xs:element name="to" type="xs:string"/>
<xs:element name="from" type="xs:string"/>
<xs:element name="heading" type="xs:string"/>
<xs:element name="body" type="xs:string"/>

</xs:schema>

Unsupported schema element type: null
java.lang.IllegalArgumentException: Unsupported schema element type: null
	at com.databricks.spark.xml.util.XSDToSchema$.getStructField(XSDToSchema.scala:216)
	at com.databricks.spark.xml.util.XSDToSchema$.$anonfun$getStructField$4(XSDToSchema.scala:182)
	at scala.collection.TraversableLike.$anonfun$flatMap$1(TraversableLike.scala:293)
	at scala.collection.Iterator.foreach(Iterator.scala:943)
	at scala.collection.Iterator.foreach$(Iterator.scala:943)
	at scala.collection.AbstractIterator.foreach(Iterator.scala:1431)
	at scala.collection.IterableLike.foreach(IterableLike.scala:74)
	at scala.collection.IterableLike.foreach$(IterableLike.scala:73)
	at scala.collection.AbstractIterable.foreach(Iterable.scala:56)
	at scala.collection.TraversableLike.flatMap(TraversableLike.scala:293)
	at scala.collection.TraversableLike.flatMap$(TraversableLike.scala:290)
	at scala.collection.AbstractTraversable.flatMap(Traversable.scala:108)
	at com.databricks.spark.xml.util.XSDToSchema$.getStructField(XSDToSchema.scala:173)
	at com.databricks.spark.xml.util.XSDToSchema$.$anonfun$getStructType$1(XSDToSchema.scala:227)
	at scala.collection.TraversableLike.$anonfun$map$1(TraversableLike.scala:286)
	at scala.collection.mutable.ResizableArray.foreach(ResizableArray.scala:62)
	at scala.collection.mutable.ResizableArray.foreach$(ResizableArray.scala:55)
	at scala.collection.mutable.ArrayBuffer.foreach(ArrayBuffer.scala:49)
	at scala.collection.TraversableLike.map(TraversableLike.scala:286)
	at scala.collection.TraversableLike.map$(TraversableLike.scala:279)
	at scala.collection.AbstractTraversable.map(Traversable.scala:108)
	at com.databricks.spark.xml.util.XSDToSchema$.getStructType(XSDToSchema.scala:221)
	at com.databricks.spark.xml.util.XSDToSchema$.read(XSDToSchema.scala:49)
	at com.databricks.spark.xml.util.XSDToSchema$.read(XSDToSchema.scala:61)

val baseType = getStructField(xmlSchema, e.getSchemaType).dataType