Fix map column can not be non-nullable for java

java/src/main/java/ai/rapids/cudf/ColumnWriterOptions.java

@@ -522,7 +522,11 @@ protected String[] getFlatColumnNames(String[] ret) {
    * Maps are List columns with a Struct named 'key_value' with a child named 'key' and a child
    * named 'value'. The caller of this method doesn't need to worry about this as this method will
    * take care of this without the knowledge of the caller.
+   *
+   * Note: This method always returns a nullabe column, cannot return non-nullable column.
+   * Do not use this, use the next function with the parameter `isNullable`.
    */
+  @Deprecated
   public static ColumnWriterOptions mapColumn(String name, ColumnWriterOptions key,
                                               ColumnWriterOptions value) {
     StructColumnWriterOptions struct = structBuilder("key_value").build();
@@ -537,6 +541,32 @@ public static ColumnWriterOptions mapColumn(String name, ColumnWriterOptions key
     return opt;
   }
 
+  /**
+   * Add a Map Column to the schema.
+   * <p>
+   * Maps are List columns with a Struct named 'key_value' with a child named 'key' and a child
+   * named 'value'. The caller of this method doesn't need to worry about this as this method will
+   * take care of this without the knowledge of the caller.
+   *
+   * Note: If this map column is a key of another map, should pass isNullable = false.
+   * e.g.: map1(map2(int, int), int) the map2 should be non-nullable.
+   *
+   * @param isNullable is the returned map nullable.
+   */
+  public static ColumnWriterOptions mapColumn(String name, ColumnWriterOptions key,
+                                              ColumnWriterOptions value, Boolean isNullable) {
+    if (key.isNullable) {
+      throw new IllegalArgumentException("key column can not be nullable");
+    }
+    StructColumnWriterOptions struct = structBuilder("key_value").build();
+    struct.childColumnOptions = new ColumnWriterOptions[]{key, value};
+    ColumnWriterOptions opt = listBuilder(name, isNullable)
+        .withStructColumn(struct)
+        .build();
+    opt.isMap = true;
+    return opt;
+  }
+
   /**
    * Creates a ListBuilder for column called 'name'
    */

java/src/test/java/ai/rapids/cudf/TableTest.java

@@ -8064,7 +8064,8 @@ void testParquetWriteMap() throws IOException {
     ParquetWriterOptions options = ParquetWriterOptions.builder()
         .withMapColumn(mapColumn("my_map",
             new ColumnWriterOptions("key0", false),
-            new ColumnWriterOptions("value0"))).build();
+            new ColumnWriterOptions("value0"),
+            true)).build();
     File f = File.createTempFile("test-map", ".parquet");
     List<HostColumnVector.StructData> list1 =
         Arrays.asList(new HostColumnVector.StructData(Arrays.asList("a", "b")));
@@ -8562,7 +8563,8 @@ void testORCWriteMapChunked() throws IOException {
     ORCWriterOptions options = ORCWriterOptions.builder()
             .withMapColumn(mapColumn("my_map",
                     new ColumnWriterOptions("key0", false),
-                    new ColumnWriterOptions("value0"))).build();
+                    new ColumnWriterOptions("value0"),
+                    true)).build();
     File f = File.createTempFile("test-map", ".parquet");
     List<HostColumnVector.StructData> list1 =
             Arrays.asList(new HostColumnVector.StructData(Arrays.asList("a", "b")));