[HUDI-1477] Support copyOnWriteTable in java client (#2382)

hudi-client/hudi-client-common/src/main/java/org/apache/hudi/config/HoodieIndexConfig.java

@@ -301,6 +301,7 @@ public class HoodieIndexConfig extends DefaultHoodieConfig {
         case SPARK:
           return HoodieIndex.IndexType.BLOOM.name();
         case FLINK:
+        case JAVA:
           return HoodieIndex.IndexType.INMEMORY.name();
         default:
           throw new HoodieNotSupportedException("Unsupported engine " + engineType);