[HUDI-4447] fix no partitioned path extractor error when sync meta (apache#6263)

Author: KnightChess

hudi-sync/hudi-sync-common/src/main/java/org/apache/hudi/sync/common/HoodieSyncConfig.java

@@ -86,7 +86,7 @@ public class HoodieSyncConfig extends HoodieConfig {
       .key("hoodie.datasource.hive_sync.partition_extractor_class")
       .defaultValue("org.apache.hudi.hive.SlashEncodedDayPartitionValueExtractor")
       .withInferFunction(cfg -> {
-        if (cfg.contains(KeyGeneratorOptions.PARTITIONPATH_FIELD_NAME)) {
+        if (StringUtils.nonEmpty(cfg.getString(KeyGeneratorOptions.PARTITIONPATH_FIELD_NAME))) {
           int numOfPartFields = cfg.getString(KeyGeneratorOptions.PARTITIONPATH_FIELD_NAME).split(",").length;
           if (numOfPartFields == 1
               && cfg.contains(KeyGeneratorOptions.HIVE_STYLE_PARTITIONING_ENABLE)

hudi-sync/hudi-sync-common/src/test/java/org/apache/hudi/sync/common/TestHoodieSyncConfig.java

@@ -100,6 +100,12 @@ void testInferPartitonExtractorClass() {
     HoodieSyncConfig config3 = new HoodieSyncConfig(new Properties(), new Configuration());
     assertEquals("org.apache.hudi.hive.NonPartitionedExtractor",
         config3.getStringOrDefault(META_SYNC_PARTITION_EXTRACTOR_CLASS));
+
+    Properties props4 = new Properties();
+    props4.setProperty(KeyGeneratorOptions.PARTITIONPATH_FIELD_NAME.key(), "");
+    HoodieSyncConfig config4 = new HoodieSyncConfig(props4, new Configuration());
+    assertEquals("org.apache.hudi.hive.NonPartitionedExtractor",
+        config4.getStringOrDefault(META_SYNC_PARTITION_EXTRACTOR_CLASS));
   }
 
   @Test