[SPARK-20536][SQL] Extend ColumnName to create StructFields with explicit nullable

sql/core/src/main/scala/org/apache/spark/sql/Column.scala

@@ -1208,85 +1208,172 @@ class ColumnName(name: String) extends Column(name) {
    */
   def boolean: StructField = StructField(name, BooleanType)
 
+  /**
+   * Creates a new `StructField` of type boolean.
+   * @since 2.4.0
+   */
+  def boolean(nullable: Boolean): StructField = StructField(name, BooleanType, nullable)
+
   /**
    * Creates a new `StructField` of type byte.
    * @since 1.3.0
    */
   def byte: StructField = StructField(name, ByteType)
 
+  /**
+   * Creates a new `StructField` of type byte.
+   * @since 2.4.0
+   */
+  def byte(nullable: Boolean): StructField = StructField(name, ByteType, nullable)
+
   /**
    * Creates a new `StructField` of type short.
    * @since 1.3.0
    */
   def short: StructField = StructField(name, ShortType)
 
+  /**
+   * Creates a new `StructField` of type short.
+   * @since 2.4.0
+   */
+  def short(nullable: Boolean): StructField = StructField(name, ShortType, nullable)
+
   /**
    * Creates a new `StructField` of type int.
    * @since 1.3.0
    */
   def int: StructField = StructField(name, IntegerType)
 
+  /**
+   * Creates a new `StructField` of type int.
+   * @since 2.4.0
+   */
+  def int(nullable: Boolean): StructField = StructField(name, IntegerType, nullable)
+
   /**
    * Creates a new `StructField` of type long.
    * @since 1.3.0
    */
   def long: StructField = StructField(name, LongType)
 
+  /**
+   * Creates a new `StructField` of type long.
+   * @since 2.4.0
+   */
+  def long(nullable: Boolean): StructField = StructField(name, LongType, nullable)
+
   /**
    * Creates a new `StructField` of type float.
    * @since 1.3.0
    */
   def float: StructField = StructField(name, FloatType)
 
+  /**
+   * Creates a new `StructField` of type float.
+   * @since 2.4.0
+   */
+  def float(nullable: Boolean): StructField = StructField(name, FloatType, nullable)
+
   /**
    * Creates a new `StructField` of type double.
    * @since 1.3.0
    */
   def double: StructField = StructField(name, DoubleType)
 
+  /**
+   * Creates a new `StructField` of type double.
+   * @since 2.4.0
+   */
+  def double(nullable: Boolean): StructField = StructField(name, DoubleType, nullable)
+
   /**
    * Creates a new `StructField` of type string.
    * @since 1.3.0
    */
   def string: StructField = StructField(name, StringType)
 
+  /**
+   * Creates a new `StructField` of type string.
+   * @since 2.4.0
+   */
+  def string(nullable: Boolean): StructField = StructField(name, StringType, nullable)
+
   /**
    * Creates a new `StructField` of type date.
    * @since 1.3.0
    */
   def date: StructField = StructField(name, DateType)
 
+  /**
+   * Creates a new `StructField` of type date.
+   * @since 2.4.0
+   */
+  def date(nullable: Boolean): StructField = StructField(name, DateType, nullable)
+
   /**
    * Creates a new `StructField` of type decimal.
    * @since 1.3.0
    */
   def decimal: StructField = StructField(name, DecimalType.USER_DEFAULT)
 
+  /**
+   * Creates a new `StructField` of type decimal.
+   * @since 2.4.0
+   */
+  def decimal(nullable: Boolean): StructField =
+    StructField(name, DecimalType.USER_DEFAULT, nullable)
+
   /**
    * Creates a new `StructField` of type decimal.
    * @since 1.3.0
    */
   def decimal(precision: Int, scale: Int): StructField =
     StructField(name, DecimalType(precision, scale))
 
+  /**
+   * Creates a new `StructField` of type decimal.
+   * @since 2.4.0
+   */
+  def decimal(precision: Int, scale: Int, nullable: Boolean): StructField =
+    StructField(name, DecimalType(precision, scale), nullable)
+
   /**
    * Creates a new `StructField` of type timestamp.
    * @since 1.3.0
    */
   def timestamp: StructField = StructField(name, TimestampType)
 
+  /**
+   * Creates a new `StructField` of type timestamp.
+   * @since 2.4.0
+   */
+  def timestamp(nullable: Boolean): StructField = StructField(name, TimestampType, nullable)
+
   /**
    * Creates a new `StructField` of type binary.
    * @since 1.3.0
    */
   def binary: StructField = StructField(name, BinaryType)
 
+  /**
+   * Creates a new `StructField` of type binary.
+   * @since 2.4.0
+   */
+  def binary(nullable: Boolean): StructField = StructField(name, BinaryType, nullable)
+
   /**
    * Creates a new `StructField` of type array.
    * @since 1.3.0
    */
   def array(dataType: DataType): StructField = StructField(name, ArrayType(dataType))
 
+  /**
+   * Creates a new `StructField` of type array.
+   * @since 2.4.0
+   */
+  def array(dataType: DataType, nullable: Boolean): StructField =
+    StructField(name, ArrayType(dataType), nullable)
+
   /**
    * Creates a new `StructField` of type map.
    * @since 1.3.0
@@ -1296,6 +1383,12 @@ class ColumnName(name: String) extends Column(name) {
 
   def map(mapType: MapType): StructField = StructField(name, mapType)
 
+  /**
+   * Creates a new `StructField` of type map.
+   * @since 2.4.0
+   */
+  def map(mapType: MapType, nullable: Boolean): StructField = StructField(name, mapType, nullable)
+
   /**
    * Creates a new `StructField` of type struct.
    * @since 1.3.0
@@ -1307,4 +1400,11 @@ class ColumnName(name: String) extends Column(name) {
    * @since 1.3.0
    */
   def struct(structType: StructType): StructField = StructField(name, structType)
+
+  /**
+   * Creates a new `StructField` of type struct.
+   * @since 2.4.0
+   */
+  def struct(structType: StructType, nullable: Boolean): StructField =
+    StructField(name, structType, nullable)
 }