Core: Fix null partitions in PartitionSet

core/src/main/java/org/apache/iceberg/util/PartitionSet.java

@@ -63,7 +63,7 @@ public boolean contains(Object o) {
     if (o instanceof Pair) {
       Object first = ((Pair<?, ?>) o).first();
       Object second = ((Pair<?, ?>) o).second();
-      if (first instanceof Integer && second instanceof StructLike) {
+      if (first instanceof Integer && (second == null || second instanceof StructLike)) {
         return contains((Integer) first, (StructLike) second);
       }
     }
@@ -98,7 +98,7 @@ public boolean remove(Object o) {
     if (o instanceof Pair) {
       Object first = ((Pair<?, ?>) o).first();
       Object second = ((Pair<?, ?>) o).second();
-      if (first instanceof Integer && second instanceof StructLike) {
+      if (first instanceof Integer && (second == null || second instanceof StructLike)) {
         return remove((Integer) first, (StructLike) second);
       }
     }

core/src/test/java/org/apache/iceberg/util/TestPartitionMap.java

@@ -274,9 +274,11 @@ public void testKeyAndEntrySetEquality() {
 
     map1.put(BY_DATA_SPEC.specId(), Row.of("aaa"), "v1");
     map1.put(BY_DATA_SPEC.specId(), Row.of("bbb"), "v2");
+    map1.put(UNPARTITIONED_SPEC.specId(), null, "v3");
 
     map2.put(BY_DATA_SPEC.specId(), CustomRow.of("aaa"), "v1");
     map2.put(BY_DATA_SPEC.specId(), CustomRow.of("bbb"), "v2");
+    map2.put(UNPARTITIONED_SPEC.specId(), null, "v3");
 
     assertThat(map1.keySet()).isEqualTo(map2.keySet());
     assertThat(map1.entrySet()).isEqualTo(map2.entrySet());

core/src/test/java/org/apache/iceberg/util/TestPartitionSet.java

@@ -0,0 +1,83 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.iceberg.util;
+
+import static org.apache.iceberg.types.Types.NestedField.required;
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.util.Map;
+import org.apache.iceberg.PartitionSpec;
+import org.apache.iceberg.Schema;
+import org.apache.iceberg.TestHelpers.CustomRow;
+import org.apache.iceberg.TestHelpers.Row;
+import org.apache.iceberg.relocated.com.google.common.collect.ImmutableMap;
+import org.apache.iceberg.types.Types;
+import org.junit.jupiter.api.Test;
+
+public class TestPartitionSet {
+  private static final Schema SCHEMA =
+      new Schema(
+          required(1, "id", Types.IntegerType.get()),
+          required(2, "data", Types.StringType.get()),
+          required(3, "category", Types.StringType.get()));
+  private static final PartitionSpec UNPARTITIONED_SPEC = PartitionSpec.unpartitioned();
+  private static final PartitionSpec BY_DATA_SPEC =
+      PartitionSpec.builderFor(SCHEMA).identity("data").withSpecId(1).build();
+  private static final PartitionSpec BY_DATA_CATEGORY_BUCKET_SPEC =
+      PartitionSpec.builderFor(SCHEMA).identity("data").bucket("category", 8).withSpecId(3).build();
+  private static final Map<Integer, PartitionSpec> SPECS =
+      ImmutableMap.of(
+          UNPARTITIONED_SPEC.specId(),
+          UNPARTITIONED_SPEC,
+          BY_DATA_SPEC.specId(),
+          BY_DATA_SPEC,
+          BY_DATA_CATEGORY_BUCKET_SPEC.specId(),
+          BY_DATA_CATEGORY_BUCKET_SPEC);
+
+  @Test
+  public void testGet() {
+    PartitionSet set = PartitionSet.create(SPECS);
+    set.add(BY_DATA_SPEC.specId(), Row.of("a"));
+    set.add(UNPARTITIONED_SPEC.specId(), null);
+    set.add(UNPARTITIONED_SPEC.specId(), Row.of());
+    set.add(BY_DATA_CATEGORY_BUCKET_SPEC.specId(), CustomRow.of("a", 1));
+
+    assertThat(set).hasSize(4);
+    assertThat(set.contains(BY_DATA_SPEC.specId(), CustomRow.of("a"))).isTrue();
+    assertThat(set.contains(UNPARTITIONED_SPEC.specId(), null)).isTrue();
+    assertThat(set.contains(UNPARTITIONED_SPEC.specId(), CustomRow.of())).isTrue();
+    assertThat(set.contains(BY_DATA_CATEGORY_BUCKET_SPEC.specId(), Row.of("a", 1))).isTrue();
+  }
+
+  @Test
+  public void testRemove() {
+    PartitionSet set = PartitionSet.create(SPECS);
+    set.add(BY_DATA_SPEC.specId(), Row.of("a"));
+    set.add(UNPARTITIONED_SPEC.specId(), null);
+    set.add(UNPARTITIONED_SPEC.specId(), Row.of());
+    set.add(BY_DATA_CATEGORY_BUCKET_SPEC.specId(), CustomRow.of("a", 1));
+
+    assertThat(set).hasSize(4);
+    assertThat(set.remove(BY_DATA_SPEC.specId(), CustomRow.of("a"))).isTrue();
+    assertThat(set.remove(UNPARTITIONED_SPEC.specId(), null)).isTrue();
+    assertThat(set.remove(UNPARTITIONED_SPEC.specId(), CustomRow.of())).isTrue();
+    assertThat(set.remove(BY_DATA_CATEGORY_BUCKET_SPEC.specId(), Row.of("a", 1))).isTrue();
+    assertThat(set).isEmpty();
+  }
+}