[HUDI-5258] Fix checkstyle issues in hudi-common

hudi-common/src/main/java/org/apache/hudi/BaseHoodieTableFileIndex.java

@@ -18,8 +18,6 @@
 
 package org.apache.hudi;
 
-import org.apache.hadoop.fs.FileStatus;
-import org.apache.hadoop.fs.Path;
 import org.apache.hudi.common.config.HoodieMetadataConfig;
 import org.apache.hudi.common.config.TypedProperties;
 import org.apache.hudi.common.engine.HoodieEngineContext;
@@ -41,6 +39,9 @@
 import org.apache.hudi.exception.HoodieIOException;
 import org.apache.hudi.hadoop.CachingPath;
 import org.apache.hudi.metadata.HoodieTableMetadata;
+
+import org.apache.hadoop.fs.FileStatus;
+import org.apache.hadoop.fs.Path;
 import org.apache.log4j.LogManager;
 import org.apache.log4j.Logger;
 
@@ -453,6 +454,10 @@ private static FileStatus[] flatMap(Collection<FileStatus[]> arrays) {
     return arrays.stream().flatMap(Arrays::stream).toArray(FileStatus[]::new);
   }
 
+  /**
+   * Partition path information containing the relative partition path
+   * and values of partition columns.
+   */
   public static final class PartitionPath {
 
     final String path;
@@ -480,6 +485,9 @@ public int hashCode() {
     }
   }
 
+  /**
+   * APIs for caching {@link FileStatus}.
+   */
   protected interface FileStatusCache {
     Option<FileStatus[]> get(Path path);
 

hudi-common/src/main/java/org/apache/hudi/avro/AvroSchemaUtils.java

@@ -27,6 +27,9 @@
 
 import static org.apache.hudi.common.util.ValidationUtils.checkState;
 
+/**
+ * Utils for Avro Schema.
+ */
 public class AvroSchemaUtils {
 
   private AvroSchemaUtils() {}

hudi-common/src/main/java/org/apache/hudi/avro/HoodieAvroUtils.java

@@ -53,7 +53,6 @@
 import org.apache.avro.io.JsonDecoder;
 import org.apache.avro.io.JsonEncoder;
 import org.apache.avro.specific.SpecificRecordBase;
-
 import org.apache.hadoop.util.VersionUtil;
 
 import java.io.ByteArrayInputStream;
@@ -71,12 +70,12 @@
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.Deque;
 import java.util.HashMap;
 import java.util.Iterator;
+import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
-import java.util.Deque;
-import java.util.LinkedList;
 import java.util.Set;
 import java.util.TimeZone;
 import java.util.stream.Collectors;

hudi-common/src/main/java/org/apache/hudi/avro/HoodieAvroWriteSupport.java

@@ -18,10 +18,11 @@
 
 package org.apache.hudi.avro;
 
-import org.apache.avro.Schema;
 import org.apache.hudi.common.bloom.BloomFilter;
 import org.apache.hudi.common.util.CollectionUtils;
 import org.apache.hudi.common.util.Option;
+
+import org.apache.avro.Schema;
 import org.apache.parquet.avro.AvroWriteSupport;
 import org.apache.parquet.hadoop.api.WriteSupport;
 import org.apache.parquet.schema.MessageType;

hudi-common/src/main/java/org/apache/hudi/avro/MercifulJsonConverter.java

@@ -18,14 +18,15 @@
 
 package org.apache.hudi.avro;
 
+import org.apache.hudi.common.util.collection.Pair;
+import org.apache.hudi.exception.HoodieException;
+import org.apache.hudi.exception.HoodieIOException;
+
 import com.fasterxml.jackson.databind.ObjectMapper;
 import org.apache.avro.Schema;
 import org.apache.avro.Schema.Type;
 import org.apache.avro.generic.GenericData;
 import org.apache.avro.generic.GenericRecord;
-import org.apache.hudi.common.util.collection.Pair;
-import org.apache.hudi.exception.HoodieException;
-import org.apache.hudi.exception.HoodieIOException;
 
 import java.io.IOException;
 import java.io.Serializable;

hudi-common/src/main/java/org/apache/hudi/common/config/ConfigClassProperty.java

@@ -23,17 +23,18 @@
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
-@Retention(RetentionPolicy.RUNTIME)
-@Target(ElementType.TYPE)
-
 /**
  * Annotation for superclasses of {@link HoodieConfig} that includes the
- * human-readable name of the config class, the config group ({@link ConfigGroupName})
+ * human-readable name of the config class, the config group ({@link ConfigGroups})
  * it belongs to (e.g., spark/ flink/ write)
  * and the description of the config class.
  */
+@Retention(RetentionPolicy.RUNTIME)
+@Target(ElementType.TYPE)
 public @interface ConfigClassProperty {
   String name();
+
   ConfigGroups.Names groupName();
+
   String description();
 }

hudi-common/src/main/java/org/apache/hudi/common/config/ConfigGroups.java

@@ -25,6 +25,9 @@
  * This class maintains the human readable name and description of each config group.
  */
 public class ConfigGroups {
+  /**
+   * Config group names.
+   */
   public enum Names {
     SPARK_DATASOURCE("Spark Datasource Configs"),
     FLINK_SQL("Flink Sql Configs"),

hudi-common/src/main/java/org/apache/hudi/common/config/HoodieCommonConfig.java

@@ -26,6 +26,9 @@
 import java.util.Locale;
 import java.util.Properties;
 
+/**
+ * Hudi configs used across engines.
+ */
 @ConfigClassProperty(name = "Common Configurations",
     groupName = ConfigGroups.Names.WRITE_CLIENT,
     description = "The following set of configurations are common across Hudi.")
@@ -45,8 +48,8 @@ public class HoodieCommonConfig extends HoodieConfig {
       .key("hoodie.datasource.write.reconcile.schema")
       .defaultValue(false)
       .withDocumentation("When a new batch of write has records with old schema, but latest table schema got "
-        + "evolved, this config will upgrade the records to leverage latest table schema(default values will be "
-        + "injected to missing fields). If not, the write batch would fail.");
+          + "evolved, this config will upgrade the records to leverage latest table schema(default values will be "
+          + "injected to missing fields). If not, the write batch would fail.");
 
   public static final ConfigProperty<ExternalSpillableMap.DiskMapType> SPILLABLE_DISK_MAP_TYPE = ConfigProperty
       .key("hoodie.common.spillable.diskmap.type")
@@ -76,6 +79,9 @@ public static HoodieCommonConfig.Builder newBuilder() {
     return new HoodieCommonConfig.Builder();
   }
 
+  /**
+   * Builder for {@link HoodieCommonConfig}.
+   */
   public static class Builder {
 
     private final HoodieCommonConfig commonConfig = new HoodieCommonConfig();

hudi-common/src/main/java/org/apache/hudi/common/config/HoodieMetadataConfig.java

@@ -329,6 +329,9 @@ public boolean getUseLogRecordReaderScanV2() {
     return getBoolean(USE_LOG_RECORD_READER_SCAN_V2);
   }
 
+  /**
+   * Builder for {@link HoodieMetadataConfig}.
+   */
   public static class Builder {
 
     private EngineType engineType = EngineType.SPARK;

hudi-common/src/main/java/org/apache/hudi/common/config/HoodieMetastoreConfig.java

@@ -19,6 +19,7 @@
 package org.apache.hudi.common.config;
 
 import javax.annotation.concurrent.Immutable;
+
 import java.util.Properties;
 
 /**
@@ -72,6 +73,9 @@ public int getConnectionRetryDelay() {
     return getIntOrDefault(METASTORE_CONNECTION_RETRY_DELAY);
   }
 
+  /**
+   * Builder for {@link HoodieMetastoreConfig}.
+   */
   public static class Builder {
     private final HoodieMetastoreConfig config = new HoodieMetastoreConfig();
 

hudi-common/src/main/java/org/apache/hudi/common/data/HoodieBaseListData.java

@@ -25,6 +25,11 @@
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
+/**
+ * Data representation of either a stream or a list of objects with Type T.
+ *
+ * @param <T> Object value type.
+ */
 public abstract class HoodieBaseListData<T> {
 
   protected final Either<Stream<T>, List<T>> data;

hudi-common/src/main/java/org/apache/hudi/common/engine/HoodieLocalEngineContext.java

@@ -18,8 +18,6 @@
 
 package org.apache.hudi.common.engine;
 
-import org.apache.hadoop.conf.Configuration;
-
 import org.apache.hudi.common.config.SerializableConfiguration;
 import org.apache.hudi.common.data.HoodieAccumulator;
 import org.apache.hudi.common.data.HoodieAtomicLongAccumulator;
@@ -31,10 +29,11 @@
 import org.apache.hudi.common.function.SerializablePairFlatMapFunction;
 import org.apache.hudi.common.function.SerializablePairFunction;
 import org.apache.hudi.common.util.Option;
-
 import org.apache.hudi.common.util.collection.ImmutablePair;
 import org.apache.hudi.common.util.collection.Pair;
 
+import org.apache.hadoop.conf.Configuration;
+
 import java.util.Collections;
 import java.util.Iterator;
 import java.util.List;

hudi-common/src/main/java/org/apache/hudi/common/engine/LocalTaskContextSupplier.java

@@ -22,6 +22,9 @@
 
 import java.util.function.Supplier;
 
+/**
+ * Supplier of task context using local Java engine.
+ */
 public final class LocalTaskContextSupplier extends TaskContextSupplier {
   @Override
   public Supplier<Integer> getPartitionIdSupplier() {

hudi-common/src/main/java/org/apache/hudi/common/fs/BoundedFsDataInputStream.java

@@ -23,6 +23,9 @@
 import java.io.IOException;
 import java.io.InputStream;
 
+/**
+ * Implementation of {@link FSDataInputStream} with bound check based on file size.
+ */
 public class BoundedFsDataInputStream extends FSDataInputStream {
   private FileSystem fs;
   private Path file;

hudi-common/src/main/java/org/apache/hudi/common/fs/FSUtils.java

@@ -845,6 +845,12 @@ public static List<FileStatus> getFileStatusAtLevel(
     return result;
   }
 
+  /**
+   * Serializable function interface.
+   *
+   * @param <T> Input value type.
+   * @param <R> Output value type.
+   */
   public interface SerializableFunction<T, R> extends Function<T, R>, Serializable {
   }
 

hudi-common/src/main/java/org/apache/hudi/common/fs/HoodieRetryWrapperFileSystem.java

@@ -18,6 +18,8 @@
 
 package org.apache.hudi.common.fs;
 
+import org.apache.hudi.common.util.RetryHelper;
+
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.CreateFlag;
 import org.apache.hadoop.fs.FSDataInputStream;
@@ -31,13 +33,15 @@
 import org.apache.hadoop.fs.RemoteIterator;
 import org.apache.hadoop.fs.permission.FsPermission;
 import org.apache.hadoop.util.Progressable;
-import org.apache.hudi.common.util.RetryHelper;
 
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.net.URI;
 import java.util.EnumSet;
 
+/**
+ * Extending {@link FileSystem} implementation of I/O operations with retries.
+ */
 public class HoodieRetryWrapperFileSystem extends FileSystem {
 
   private FileSystem fileSystem;
@@ -139,7 +143,7 @@ public FSDataOutputStream create(Path f, FsPermission permission, EnumSet<Create
                                    short replication, long blockSize, Progressable progress, Options.ChecksumOpt checksumOpt) throws IOException {
     return (FSDataOutputStream) new RetryHelper(maxRetryIntervalMs, maxRetryNumbers, initialRetryIntervalMs, retryExceptionsList)
         .tryWith(() -> fileSystem.create(f, permission, flags, bufferSize, replication,
-                blockSize, progress, checksumOpt)).start();
+            blockSize, progress, checksumOpt)).start();
   }
 
   @Override

hudi-common/src/main/java/org/apache/hudi/common/fs/HoodieWrapperFileSystem.java

@@ -73,6 +73,9 @@ public class HoodieWrapperFileSystem extends FileSystem {
 
   private static final String TMP_PATH_POSTFIX = ".tmp";
 
+  /**
+   * Names for metrics.
+   */
   protected enum MetricName {
     create, rename, delete, listStatus, mkdirs, getFileStatus, globStatus, listFiles, read, write
   }
@@ -91,6 +94,11 @@ public static void setMetricsRegistry(Registry registry, Registry registryMeta)
   private URI uri;
   private ConsistencyGuard consistencyGuard = new NoOpConsistencyGuard();
 
+  /**
+   * Checked function interface.
+   *
+   * @param <R> Type of return value.
+   */
   @FunctionalInterface
   public interface CheckedFunction<R> {
     R get() throws IOException;

hudi-common/src/main/java/org/apache/hudi/common/function/SerializableSupplier.java

@@ -20,6 +20,11 @@
 
 import java.io.Serializable;
 
+/**
+ * Serializable supplier interface.
+ *
+ * @param <T> Type of return value.
+ */
 @FunctionalInterface
 public interface SerializableSupplier<T> extends Serializable {
   T get();

hudi-common/src/main/java/org/apache/hudi/common/metrics/Registry.java

@@ -18,14 +18,13 @@
 
 package org.apache.hudi.common.metrics;
 
+import org.apache.hudi.common.util.ReflectionUtils;
+
 import java.io.Serializable;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 
-import org.apache.hudi.common.util.ReflectionUtils;
-
-
 /**
  * Interface which defines a lightweight Metrics Registry to track Hudi events.
  */

hudi-common/src/main/java/org/apache/hudi/common/model/AWSDmsAvroPayload.java

@@ -18,10 +18,11 @@
 
 package org.apache.hudi.common.model;
 
+import org.apache.hudi.common.util.Option;
+
 import org.apache.avro.Schema;
 import org.apache.avro.generic.GenericRecord;
 import org.apache.avro.generic.IndexedRecord;
-import org.apache.hudi.common.util.Option;
 
 import java.io.IOException;
 import java.util.Properties;

hudi-common/src/main/java/org/apache/hudi/common/model/BaseFile.java

@@ -18,9 +18,10 @@
 
 package org.apache.hudi.common.model;
 
+import org.apache.hudi.hadoop.CachingPath;
+
 import org.apache.hadoop.fs.FileStatus;
 import org.apache.hadoop.fs.Path;
-import org.apache.hudi.hadoop.CachingPath;
 
 import java.io.Serializable;
 import java.util.Objects;

hudi-common/src/main/java/org/apache/hudi/common/model/BootstrapBaseFileMapping.java

@@ -18,10 +18,11 @@
 
 package org.apache.hudi.common.model;
 
-import java.io.Serializable;
 import org.apache.hudi.avro.model.HoodieFileStatus;
 import org.apache.hudi.common.bootstrap.FileStatusUtils;
 
+import java.io.Serializable;
+
 /**
  * POJO storing (partitionPath, hoodieFileId) -> external base file path.
  */

hudi-common/src/main/java/org/apache/hudi/common/model/BootstrapFileMapping.java

@@ -18,9 +18,10 @@
 
 package org.apache.hudi.common.model;
 
+import org.apache.hudi.avro.model.HoodieFileStatus;
+
 import java.io.Serializable;
 import java.util.Objects;
-import org.apache.hudi.avro.model.HoodieFileStatus;
 
 /**
  * Value stored in the bootstrap index.