test("SparkTest 0280") {
    val conf = new SparkConf().set("spark.sql.codegen.wholeStage", "false").set("spark.sql.cbo.enabled", "true")
    val spark = SparkSession.builder().config(conf).master("local").appName("SparkTest").enableHiveSupport().getOrCreate()

    import spark.implicits._


    Seq[(Int,Int)]((null, 1), (2, null), (null, 3)).toDF("a", "b").createOrReplaceTempView("t")
    spark.sql("select a,b,nvl(a,b) from t").show(truncate = false)

Error:(565, 21) an expression of type Null is ineligible for implicit conversion
    Seq[(Int,Int)]((null, 1), (2, null), (null, 3)).toDF("a", "b").createOrReplaceTempView("t")