[SPARK-49615] Bugfix: Make ML column schema validation conforms with spark config spark.sql.caseSensitive.

mllib/src/main/scala/org/apache/spark/ml/util/SchemaUtils.scala

@@ -19,8 +19,10 @@ package org.apache.spark.ml.util
 
 import org.apache.spark.ml.attribute._
 import org.apache.spark.ml.linalg.VectorUDT
+import org.apache.spark.sql.SparkSession
 import org.apache.spark.sql.catalyst.util.AttributeNameParser
 import org.apache.spark.sql.types._
+import org.apache.spark.sql.internal.SQLConf
 
 
 /**
@@ -213,11 +215,7 @@ private[spark] object SchemaUtils {
    */
   def getSchemaField(schema: StructType, colName: String): StructField = {
     val colSplits = AttributeNameParser.parseAttributeName(colName)
-    var field = schema(colSplits(0))
-    for (colSplit <- colSplits.slice(1, colSplits.length)) {
-      field = field.dataType.asInstanceOf[StructType](colSplit)
-    }
-    field
+    schema.findNestedField(colSplits, resolver = SQLConf.get.resolver).get._2
   }
 
   /**

sql/api/src/main/scala/org/apache/spark/sql/types/StructType.scala

@@ -321,7 +321,7 @@ case class StructType(fields: Array[StructField]) extends DataType with Seq[Stru
    *
    * If includeCollections is true, this will return fields that are nested in maps and arrays.
    */
-  private[sql] def findNestedField(
+  private[spark] def findNestedField(
       fieldNames: Seq[String],
       includeCollections: Boolean = false,
       resolver: SqlApiAnalysis.Resolver = _ == _,