[HUDI-4739] Wrong value returned when key's length equals 1

hudi-client/hudi-client-common/src/main/java/org/apache/hudi/keygen/KeyGenUtils.java

@@ -73,21 +73,16 @@ public static String getPartitionPathFromGenericRecord(GenericRecord genericReco
    */
   public static String[] extractRecordKeys(String recordKey) {
     String[] fieldKV = recordKey.split(",");
-    if (fieldKV.length == 1) {
-      return fieldKV;
-    } else {
-      // a complex key
-      return Arrays.stream(fieldKV).map(kv -> {
-        final String[] kvArray = kv.split(":");
-        if (kvArray[1].equals(NULL_RECORDKEY_PLACEHOLDER)) {
-          return null;
-        } else if (kvArray[1].equals(EMPTY_RECORDKEY_PLACEHOLDER)) {
-          return "";
-        } else {
-          return kvArray[1];
-        }
-      }).toArray(String[]::new);
-    }
+    return Arrays.stream(fieldKV).map(kv -> {
+      final String[] kvArray = kv.split(":");
+      if (kvArray[1].equals(NULL_RECORDKEY_PLACEHOLDER)) {
+        return null;
+      } else if (kvArray[1].equals(EMPTY_RECORDKEY_PLACEHOLDER)) {
+        return "";
+      } else {
+        return kvArray[1];
+      }
+    }).toArray(String[]::new);
   }
 
   public static String getRecordKey(GenericRecord record, List<String> recordKeyFields, boolean consistentLogicalTimestampEnabled) {

hudi-client/hudi-client-common/src/test/java/org/apache/hudi/keygen/TestKeyGenUtils.java

@@ -0,0 +1,37 @@
+/*
+ * 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.hudi.keygen;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+public class TestKeyGenUtils {
+
+  @Test
+  public void testExtractRecordKeys() {
+    String[] s1 = KeyGenUtils.extractRecordKeys("id:1");
+    Assertions.assertArrayEquals(new String[]{"1"}, s1);
+
+    String[] s2 = KeyGenUtils.extractRecordKeys("id:1,id:2");
+    Assertions.assertArrayEquals(new String[]{"1", "2"}, s2);
+
+    String[] s3 = KeyGenUtils.extractRecordKeys("id:1,id2:__null__,id3:__empty__");
+    Assertions.assertArrayEquals(new String[]{"1", null, ""}, s3);
+  }
+}