diff --git a/hudi-client/src/main/java/org/apache/hudi/client/HoodieWriteClient.java b/hudi-client/src/main/java/org/apache/hudi/client/HoodieWriteClient.java
index 9f6df7bdf..142ff330a 100644
--- a/hudi-client/src/main/java/org/apache/hudi/client/HoodieWriteClient.java
+++ b/hudi-client/src/main/java/org/apache/hudi/client/HoodieWriteClient.java
@@ -557,7 +557,7 @@ public class HoodieWriteClient<T extends HoodieRecordPayload> extends AbstractHo
       metrics.updateCleanMetrics(durationMs, metadata.getTotalFilesDeleted());
       LOG.info("Cleaned " + metadata.getTotalFilesDeleted() + " files"
           + " Earliest Retained Instant :" + metadata.getEarliestCommitToRetain()
-          + " cleanerElaspsedMs" + durationMs);
+          + " cleanerElapsedMs" + durationMs);
     }
     return metadata;
   }
diff --git a/hudi-integ-test/README.md b/hudi-integ-test/README.md
index d87fec3ad..a497ad9c2 100644
--- a/hudi-integ-test/README.md
+++ b/hudi-integ-test/README.md
@@ -41,7 +41,7 @@ Depending on the type of workload generated, data is either ingested into the ta
 dataset or the corresponding workload operation is executed. For example compaction does not necessarily need a workload
 to be generated/ingested but can require an execution.
 
-## Other actions/operatons
+## Other actions/operations
 
 The test suite supports different types of operations besides ingestion such as Hive Query execution, Clean action etc.
 
@@ -66,9 +66,9 @@ link#HudiDeltaStreamer page to learn about all the available configs applicable
 
 There are 2 ways to generate a workload pattern
 
- 1.Programatically
+ 1.Programmatically
 
-Choose to write up the entire DAG of operations programatically, take a look at `WorkflowDagGenerator` class.
+Choose to write up the entire DAG of operations programmatically, take a look at `WorkflowDagGenerator` class.
 Once you're ready with the DAG you want to execute, simply pass the class name as follows:
 
 ```
diff --git a/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/converter/Converter.java b/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/converter/Converter.java
index e4ad0a7fa..89f3b884e 100644
--- a/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/converter/Converter.java
+++ b/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/converter/Converter.java
@@ -29,5 +29,11 @@ import org.apache.spark.api.java.JavaRDD;
  */
 public interface Converter<I, O> extends Serializable {
 
+  /**
+   * Convert data from one format to another.
+   *
+   * @param inputRDD Input data
+   * @return Data in target format
+   */
   JavaRDD<O> convert(JavaRDD<I> inputRDD);
 }
\ No newline at end of file
diff --git a/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/BulkInsertNode.java b/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/BulkInsertNode.java
index 7a8f40550..bdf57f8d1 100644
--- a/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/BulkInsertNode.java
+++ b/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/BulkInsertNode.java
@@ -24,6 +24,9 @@ import org.apache.hudi.integ.testsuite.HoodieTestSuiteWriter;
 import org.apache.hudi.integ.testsuite.configuration.DeltaConfig.Config;
 import org.apache.spark.api.java.JavaRDD;
 
+/**
+ * Represents a bulk insert node in the DAG of operations for a workflow.
+ */
 public class BulkInsertNode extends InsertNode {
 
   public BulkInsertNode(Config config) {
diff --git a/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/CleanNode.java b/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/CleanNode.java
index 7083b47cb..2c0fcba2c 100644
--- a/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/CleanNode.java
+++ b/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/CleanNode.java
@@ -20,6 +20,10 @@ package org.apache.hudi.integ.testsuite.dag.nodes;
 
 import org.apache.hudi.integ.testsuite.dag.ExecutionContext;
 
+/**
+ * Represents a clean node in the DAG of operations for a workflow. Clean up any stale/old files/data lying around
+ * (either on file storage or index storage) based on configurations and CleaningPolicy used.
+ */
 public class CleanNode extends DagNode<Boolean> {
 
   public CleanNode() {
diff --git a/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/CompactNode.java b/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/CompactNode.java
index 92fe53c3e..4c3ad6155 100644
--- a/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/CompactNode.java
+++ b/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/CompactNode.java
@@ -26,12 +26,22 @@ import org.apache.hudi.integ.testsuite.configuration.DeltaConfig.Config;
 import org.apache.hudi.integ.testsuite.dag.ExecutionContext;
 import org.apache.spark.api.java.JavaRDD;
 
+/**
+ * Represents a compact node in the DAG of operations for a workflow.
+ */
 public class CompactNode extends DagNode<JavaRDD<WriteStatus>> {
 
   public CompactNode(Config config) {
     this.config = config;
   }
 
+  /**
+   * Method helps to start the compact operation. It will compact the last pending compact instant in the timeline
+   * if it has one.
+   *
+   * @param executionContext Execution context to run this compaction
+   * @throws Exception  will be thrown if any error occurred.
+   */
   @Override
   public void execute(ExecutionContext executionContext) throws Exception {
     HoodieTableMetaClient metaClient = new HoodieTableMetaClient(executionContext.getHoodieTestSuiteWriter().getConfiguration(),
diff --git a/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/DagNode.java b/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/DagNode.java
index aa54dc913..df54b4c81 100644
--- a/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/DagNode.java
+++ b/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/DagNode.java
@@ -29,7 +29,7 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 /**
- * Represents a Node in the DAG of operations for a workflow.
+ * Base abstraction of an compute node in the DAG of operations for a workflow.
  */
 public abstract class DagNode<O> implements Comparable<DagNode<O>> {
 
@@ -76,6 +76,12 @@ public abstract class DagNode<O> implements Comparable<DagNode<O>> {
     this.parentNodes = parentNodes;
   }
 
+  /**
+   * Execute the {@link DagNode}.
+   *
+   * @param context The context needed for an execution of a node.
+   * @throws Exception Thrown if the execution failed.
+   */
   public abstract void execute(ExecutionContext context) throws Exception;
 
   public boolean isCompleted() {
diff --git a/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/HiveQueryNode.java b/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/HiveQueryNode.java
index 04f8c2e73..f36b7d451 100644
--- a/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/HiveQueryNode.java
+++ b/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/HiveQueryNode.java
@@ -30,6 +30,9 @@ import org.apache.hudi.integ.testsuite.configuration.DeltaConfig;
 import org.apache.hudi.integ.testsuite.dag.ExecutionContext;
 import org.apache.hudi.integ.testsuite.helpers.HiveServiceProvider;
 
+/**
+ * A hive query node in the DAG of operations for a workflow. used to perform a hive query with given config.
+ */
 public class HiveQueryNode extends DagNode<Boolean> {
 
   private HiveServiceProvider hiveServiceProvider;
diff --git a/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/HiveSyncNode.java b/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/HiveSyncNode.java
index f24da1496..f52a918cb 100644
--- a/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/HiveSyncNode.java
+++ b/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/HiveSyncNode.java
@@ -22,6 +22,9 @@ import org.apache.hudi.integ.testsuite.helpers.HiveServiceProvider;
 import org.apache.hudi.integ.testsuite.configuration.DeltaConfig.Config;
 import org.apache.hudi.integ.testsuite.dag.ExecutionContext;
 
+/**
+ * Represents a hive sync node in the DAG of operations for a workflow. Helps to sync hoodie data to hive table.
+ */
 public class HiveSyncNode extends DagNode<Boolean> {
 
   private HiveServiceProvider hiveServiceProvider;
diff --git a/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/InsertNode.java b/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/InsertNode.java
index 23cb28574..62db5b67d 100644
--- a/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/InsertNode.java
+++ b/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/InsertNode.java
@@ -26,6 +26,9 @@ import org.apache.hudi.integ.testsuite.dag.ExecutionContext;
 import org.apache.hudi.integ.testsuite.generator.DeltaGenerator;
 import org.apache.spark.api.java.JavaRDD;
 
+/**
+ * An insert node in the DAG of operations for a workflow.
+ */
 public class InsertNode extends DagNode<JavaRDD<WriteStatus>> {
 
   public InsertNode(Config config) {
diff --git a/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/RollbackNode.java b/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/RollbackNode.java
index b6d828a10..cf96961a4 100644
--- a/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/RollbackNode.java
+++ b/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/RollbackNode.java
@@ -24,12 +24,21 @@ import org.apache.hudi.common.util.Option;
 import org.apache.hudi.integ.testsuite.configuration.DeltaConfig.Config;
 import org.apache.hudi.integ.testsuite.dag.ExecutionContext;
 
+/**
+ * A rollback node in the DAG helps to perform rollback operations.
+ */
 public class RollbackNode extends DagNode<Option<HoodieInstant>> {
 
   public RollbackNode(Config config) {
     this.config = config;
   }
 
+  /**
+   * Method helps to rollback the last commit instant in the timeline, if it has one.
+   *
+   * @param executionContext Execution context to perform this rollback
+   * @throws Exception will be thrown if any error occurred
+   */
   @Override
   public void execute(ExecutionContext executionContext) throws Exception {
     log.info("Executing rollback node {}", this.getName());
diff --git a/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/ScheduleCompactNode.java b/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/ScheduleCompactNode.java
index 93502aee1..0aa67f417 100644
--- a/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/ScheduleCompactNode.java
+++ b/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/ScheduleCompactNode.java
@@ -25,6 +25,9 @@ import org.apache.hudi.common.util.Option;
 import org.apache.hudi.integ.testsuite.configuration.DeltaConfig.Config;
 import org.apache.hudi.integ.testsuite.dag.ExecutionContext;
 
+/**
+ * A schedule node in the DAG of operations for a workflow helps to schedule compact operation.
+ */
 public class ScheduleCompactNode extends DagNode<Option<String>> {
 
   public ScheduleCompactNode(Config config) {
diff --git a/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/SparkSQLQueryNode.java b/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/SparkSQLQueryNode.java
index a8a1b72bb..e06d6defe 100644
--- a/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/SparkSQLQueryNode.java
+++ b/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/SparkSQLQueryNode.java
@@ -26,6 +26,9 @@ import org.apache.spark.sql.Dataset;
 import org.apache.spark.sql.Row;
 import org.apache.spark.sql.SparkSession;
 
+/**
+ * A SparkSQL query node in the DAG of operations for a workflow.
+ */
 public class SparkSQLQueryNode extends DagNode<Boolean> {
 
   HiveServiceProvider hiveServiceProvider;
@@ -35,6 +38,12 @@ public class SparkSQLQueryNode extends DagNode<Boolean> {
     this.hiveServiceProvider = new HiveServiceProvider(config);
   }
 
+  /**
+   * Method helps to execute a sparkSql query from a hive table.
+   *
+   * @param executionContext Execution context to perform this query.
+   * @throws Exception will be thrown if ant error occurred
+   */
   @Override
   public void execute(ExecutionContext executionContext) throws Exception {
     log.info("Executing spark sql query node");
diff --git a/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/UpsertNode.java b/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/UpsertNode.java
index 3872f767b..1377a4d6b 100644
--- a/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/UpsertNode.java
+++ b/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/UpsertNode.java
@@ -25,6 +25,9 @@ import org.apache.hudi.integ.testsuite.configuration.DeltaConfig.Config;
 import org.apache.hudi.integ.testsuite.generator.DeltaGenerator;
 import org.apache.spark.api.java.JavaRDD;
 
+/**
+ * Represents an upsert node in the DAG of operations for a workflow.
+ */
 public class UpsertNode extends InsertNode {
 
   public UpsertNode(Config config) {
diff --git a/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/ValidateNode.java b/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/ValidateNode.java
index 5ba0249a6..37244c0a8 100644
--- a/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/ValidateNode.java
+++ b/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/nodes/ValidateNode.java
@@ -23,6 +23,9 @@ import java.util.function.Function;
 import org.apache.hudi.integ.testsuite.configuration.DeltaConfig.Config;
 import org.apache.hudi.integ.testsuite.dag.ExecutionContext;
 
+/**
+ * A validate node helps to validate its parent nodes with given function.
+ */
 public class ValidateNode<R> extends DagNode {
 
   protected Function<List<DagNode>, R> function;
@@ -32,6 +35,12 @@ public class ValidateNode<R> extends DagNode {
     this.config = config;
   }
 
+  /**
+   * Method to start the validate operation. Exceptions will be thrown if its parent nodes exist and WAIT_FOR_PARENTS
+   * was set to true or default, but the parent nodes have not completed yet.
+   *
+   * @param executionContext Context to execute this node
+   */
   @Override
   public void execute(ExecutionContext executionContext) {
     if (this.getParentNodes().size() > 0 && (Boolean) this.config.getOtherConfigs().getOrDefault("WAIT_FOR_PARENTS",
diff --git a/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/scheduler/DagScheduler.java b/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/scheduler/DagScheduler.java
index 7d78d8311..280f30183 100644
--- a/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/scheduler/DagScheduler.java
+++ b/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/dag/scheduler/DagScheduler.java
@@ -37,6 +37,10 @@ import org.apache.hudi.integ.testsuite.generator.DeltaGenerator;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+/**
+ * The Dag scheduler schedules the workflow DAGs. It will convert DAG to node set and execute the nodes according to
+ * the relations between nodes.
+ */
 public class DagScheduler {
 
   private static Logger log = LoggerFactory.getLogger(DagScheduler.class);
@@ -48,6 +52,11 @@ public class DagScheduler {
     this.executionContext = new ExecutionContext(null, hoodieTestSuiteWriter, deltaGenerator);
   }
 
+  /**
+   * Method to start executing workflow DAGs.
+   *
+   * @throws Exception Thrown if schedule failed.
+   */
   public void schedule() throws Exception {
     ExecutorService service = Executors.newFixedThreadPool(2);
     try {
@@ -61,6 +70,13 @@ public class DagScheduler {
     }
   }
 
+  /**
+   * Method to start executing the nodes in workflow DAGs.
+   *
+   * @param service ExecutorService
+   * @param nodes   Nodes to be executed
+   * @throws Exception will be thrown if ant error occurred
+   */
   private void execute(ExecutorService service, List<DagNode> nodes) throws Exception {
     // Nodes at the same level are executed in parallel
     Queue<DagNode> queue = new PriorityQueue<>(nodes);
@@ -84,6 +100,11 @@ public class DagScheduler {
     log.info("Finished workloads");
   }
 
+  /**
+   * Execute the given node.
+   *
+   * @param node The node to be executed
+   */
   private void executeNode(DagNode node) {
     if (node.isCompleted()) {
       throw new RuntimeException("DagNode already completed! Cannot re-execute");
diff --git a/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/generator/DeltaGenerator.java b/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/generator/DeltaGenerator.java
index c9d129ec9..3b7b114ed 100644
--- a/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/generator/DeltaGenerator.java
+++ b/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/generator/DeltaGenerator.java
@@ -57,7 +57,7 @@ import scala.Tuple2;
  */
 public class DeltaGenerator implements Serializable {
 
-  private static Logger log = LoggerFactory.getLogger(DFSHoodieDatasetInputReader.class);
+  private static Logger log = LoggerFactory.getLogger(DeltaGenerator.class);
 
   private DeltaConfig deltaOutputConfig;
   private transient JavaSparkContext jsc;
diff --git a/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/generator/GenericRecordFullPayloadGenerator.java b/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/generator/GenericRecordFullPayloadGenerator.java
index 706ffd26f..5ef77b2e7 100644
--- a/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/generator/GenericRecordFullPayloadGenerator.java
+++ b/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/generator/GenericRecordFullPayloadGenerator.java
@@ -98,14 +98,32 @@ public class GenericRecordFullPayloadGenerator implements Serializable {
     }
   }
 
+  /**
+   * Create a new {@link GenericRecord} with random value according to given schema.
+   *
+   * @return {@link GenericRecord} with random value
+   */
   public GenericRecord getNewPayload() {
     return convert(baseSchema);
   }
 
+  /**
+   * Update a given {@link GenericRecord} with random value. The fields in {@code blacklistFields} will not be updated.
+   *
+   * @param record          GenericRecord to update
+   * @param blacklistFields Fields whose value should not be touched
+   * @return The updated {@link GenericRecord}
+   */
   public GenericRecord getUpdatePayload(GenericRecord record, List<String> blacklistFields) {
     return randomize(record, blacklistFields);
   }
 
+  /**
+   * Create a {@link GenericRecord} with random value according to given schema.
+   *
+   * @param schema Schema to create record with
+   * @return {@link GenericRecord} with random value
+   */
   protected GenericRecord convert(Schema schema) {
     GenericRecord result = new GenericData.Record(schema);
     for (Schema.Field f : schema.getFields()) {
@@ -114,6 +132,13 @@ public class GenericRecordFullPayloadGenerator implements Serializable {
     return result;
   }
 
+  /**
+   * Create a new {@link GenericRecord} with random values. Not all the fields have value, it is random, and its value
+   * is random too.
+   *
+   * @param schema Schema to create with.
+   * @return A {@link GenericRecord} with random value.
+   */
   protected GenericRecord convertPartial(Schema schema) {
     GenericRecord result = new GenericData.Record(schema);
     for (Schema.Field f : schema.getFields()) {
@@ -128,6 +153,14 @@ public class GenericRecordFullPayloadGenerator implements Serializable {
     return result;
   }
 
+  /**
+   * Set random value to {@link GenericRecord} according to the schema type of field.
+   * The field in blacklist will not be set.
+   *
+   * @param record          GenericRecord to randomize.
+   * @param blacklistFields blacklistFields where the filed will not be randomized.
+   * @return Randomized GenericRecord.
+   */
   protected GenericRecord randomize(GenericRecord record, List<String> blacklistFields) {
     for (Schema.Field f : record.getSchema().getFields()) {
       if (blacklistFields == null || !blacklistFields.contains(f.name())) {
@@ -137,6 +170,9 @@ public class GenericRecordFullPayloadGenerator implements Serializable {
     return record;
   }
 
+  /**
+   * Generate random value according to their type.
+   */
   private Object typeConvert(Schema schema) {
     Schema localSchema = schema;
     if (isOption(schema)) {
@@ -215,10 +251,26 @@ public class GenericRecordFullPayloadGenerator implements Serializable {
     }
   }
 
+  /**
+   * Validate whether the record match schema.
+   *
+   * @param record Record to validate.
+   * @return True if matches.
+   */
   public boolean validate(GenericRecord record) {
     return genericData.validate(baseSchema, record);
   }
 
+  /**
+   * Check whether a schema is option.
+   * return true if it match the follows:
+   * 1. Its type is Type.UNION
+   * 2. Has two types
+   * 3. Has a NULL type.
+   *
+   * @param schema
+   * @return
+   */
   protected boolean isOption(Schema schema) {
     return schema.getType().equals(Schema.Type.UNION)
         && schema.getTypes().size() == 2
@@ -260,6 +312,12 @@ public class GenericRecordFullPayloadGenerator implements Serializable {
     }
   }
 
+  /**
+   * Method help to calculate the number of entries to add.
+   *
+   * @param elementSchema
+   * @return Number of entries to add
+   */
   private int numEntriesToAdd(Schema elementSchema) {
     // Find the size of the primitive data type in bytes
     int primitiveDataTypeSize = getSize(elementSchema);
diff --git a/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/generator/GenericRecordFullPayloadSizeEstimator.java b/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/generator/GenericRecordFullPayloadSizeEstimator.java
index c6a8f4e31..e595c26d9 100644
--- a/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/generator/GenericRecordFullPayloadSizeEstimator.java
+++ b/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/generator/GenericRecordFullPayloadSizeEstimator.java
@@ -61,6 +61,12 @@ public class GenericRecordFullPayloadSizeEstimator implements Serializable {
     return (int) size;
   }
 
+  /**
+   * Estimate the size of a given schema according to their type.
+   *
+   * @param schema schema to estimate.
+   * @return Size of the given schema.
+   */
   private long typeEstimate(Schema schema) {
     Schema localSchema = schema;
     if (isOption(schema)) {
@@ -112,6 +118,12 @@ public class GenericRecordFullPayloadSizeEstimator implements Serializable {
         || schema.getTypes().get(1).getType().equals(Schema.Type.NULL));
   }
 
+  /**
+   * Get the nonNull Schema of a given UNION Schema.
+   *
+   * @param schema
+   * @return
+   */
   protected Schema getNonNull(Schema schema) {
     List<Schema> types = schema.getTypes();
     return types.get(0).getType().equals(Schema.Type.NULL) ? types.get(1) : types.get(0);
diff --git a/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/generator/UpdateGeneratorIterator.java b/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/generator/UpdateGeneratorIterator.java
index 685a5c77a..a33ef0c7f 100644
--- a/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/generator/UpdateGeneratorIterator.java
+++ b/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/generator/UpdateGeneratorIterator.java
@@ -24,6 +24,9 @@ import java.util.List;
 import org.apache.avro.Schema;
 import org.apache.avro.generic.GenericRecord;
 
+/**
+ * A lazy update payload generator to generate {@link GenericRecord}s lazily.
+ */
 public class UpdateGeneratorIterator implements Iterator<GenericRecord> {
 
   // Use the full payload generator as default
diff --git a/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/writer/DeltaWriterAdapter.java b/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/writer/DeltaWriterAdapter.java
index c941458fc..3ce302f1f 100644
--- a/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/writer/DeltaWriterAdapter.java
+++ b/hudi-integ-test/src/main/java/org/apache/hudi/integ/testsuite/writer/DeltaWriterAdapter.java
@@ -23,6 +23,9 @@ import java.util.Iterator;
 import java.util.List;
 import org.apache.spark.api.java.JavaRDD;
 
+/**
+ * Adapter use Delta Writer.
+ */
 public interface DeltaWriterAdapter<I> {
 
   List<DeltaWriteStats> write(Iterator<I> input) throws IOException;