Fix: Return null for null entries in CometPlainVector.getBinary

Author: cfmcgrady

common/src/main/java/org/apache/comet/vector/CometPlainVector.java

@@ -147,6 +147,9 @@ public UTF8String getUTF8String(int rowId) {
 
   @Override
   public byte[] getBinary(int rowId) {
+    if (isNullAt(rowId)) {
+      return null;
+    }
     int offset;
     int length;
     if (valueVector instanceof BaseVariableWidthVector) {

spark/src/test/scala/org/apache/comet/CometArrayExpressionSuite.scala

@@ -777,4 +777,29 @@ class CometArrayExpressionSuite extends CometTestBase with AdaptiveSparkPlanHelp
       }
     }
   }
+
+  test("array_reverse 2") {
+    withTempDir { dir =>
+      val path = new Path(dir.toURI.toString, "test.parquet")
+      val filename = path.toString
+      val random = new Random(42)
+      withSQLConf(CometConf.COMET_ENABLED.key -> "false") {
+        val options = DataGenOptions(
+          allowNull = true,
+          generateNegativeZero = false,
+          generateArray = true,
+          generateStruct = false,
+          generateMap = false)
+        ParquetGenerator.makeParquetFile(random, spark, filename, 100, options)
+      }
+      withTempView("t1") {
+        val table = spark.read.parquet(filename)
+        table.createOrReplaceTempView("t1")
+        for (field <- table.schema.fields.filter(_.dataType.isInstanceOf[ArrayType])) {
+          val sql = s"SELECT ${field.name}, reverse(${field.name}) FROM t1 ORDER BY ${field.name}"
+          checkSparkAnswer(sql)
+        }
+      }
+    }
+  }
 }