[INLONG-1593][checkstyle] Add EmptyLineSeparator java code checkstyle…

… rule (apache#1594)

codestyle/checkstyle.xml

@@ -429,12 +429,23 @@
             <property name="tokens" value="BLOCK_COMMENT_BEGIN"/>
         </module>
 
-
         <!-- https://checkstyle.org/config_filters.html#SuppressionXpathFilter -->
         <module name="SuppressionXpathFilter">
             <property name="file" value="${org.checkstyle.google.suppressionxpathfilter.config}"
                       default="checkstyle-xpath-suppressions.xml" />
             <property name="optional" value="true"/>
         </module>
+
+        <module name="EmptyLineSeparator">
+            <!-- Checks for empty line separator between tokens. The only
+                 excluded token is VARIABLE_DEF, allowing class fields to
+                 be declared on consecutive lines.
+            -->
+            <property name="allowMultipleEmptyLines" value="false"/>
+            <property name="allowMultipleEmptyLinesInsideClassMembers" value="false"/>
+            <property name="tokens" value="PACKAGE_DEF, IMPORT, STATIC_IMPORT, CLASS_DEF,
+                                           INTERFACE_DEF, ENUM_DEF, STATIC_INIT, INSTANCE_INIT, METHOD_DEF,
+                                           CTOR_DEF"/>
+        </module>
     </module>
 </module>

inlong-agent/agent-common/src/main/java/org/apache/inlong/agent/common/AgentThreadFactory.java

@@ -17,7 +17,6 @@
 
 package org.apache.inlong.agent.common;
 
-
 import java.util.concurrent.ThreadFactory;
 import java.util.concurrent.atomic.AtomicInteger;
 import org.slf4j.Logger;

inlong-agent/agent-common/src/main/java/org/apache/inlong/agent/constants/AgentConstants.java

@@ -97,7 +97,6 @@ public class AgentConstants {
     public static final String JOB_THREAD_RUNNING_CORE = "job.thread.running.core";
     public static final int DEFAULT_JOB_THREAD_RUNNING_CORE = 4;
 
-
     public static final String JOB_MONITOR_INTERVAL = "job.monitor.interval";
     public static final int DEFAULT_JOB_MONITOR_INTERVAL = 5;
 

inlong-agent/agent-common/src/main/java/org/apache/inlong/agent/constants/CommonConstants.java

@@ -29,7 +29,6 @@ public class CommonConstants {
 
     public static final String PROXY_TID = "proxy.tid";
 
-
     public static final String PROXY_LOCAL_HOST = "proxy.localHost";
     public static final String DEFAULT_PROXY_LOCALHOST = AgentUtils.getLocalIp();
 
@@ -122,16 +121,13 @@ public class CommonConstants {
     public static final String PULSAR_PRODUCER_BLOCK_QUEUE = "pulsar.producer.block.queue";
     public static final boolean DEFAULT_PULSAR_PRODUCER_BLOCK_QUEUE = true;
 
-
     public static final String FILE_MAX_NUM = "file.max.num";
     public static final int DEFAULT_FILE_MAX_NUM = 4096;
 
     public static final String TRIGGER_ID_PREFIX = "trigger_";
 
-
     public static final String COMMAND_STORE_INSTANCE_NAME = "commandStore";
 
-
     public static final String AGENT_OS_NAME = "os.name";
     public static final String AGENT_NIX_OS = "nix";
     public static final String AGENT_NUX_OS = "nux";

inlong-agent/agent-common/src/main/java/org/apache/inlong/agent/constants/JobConstants.java

@@ -17,7 +17,6 @@
 
 package org.apache.inlong.agent.constants;
 
-
 /**
  * Basic config for a single job
  */
@@ -29,7 +28,6 @@ public class JobConstants extends CommonConstants {
     public static final String JOB_IP = "job.ip";
     public static final String JOB_RETRY = "job.retry";
 
-
     public static final String JOB_SOURCE = "job.source";
     public static final String JOB_SINK = "job.sink";
     public static final String JOB_CHANNEL = "job.channel";

inlong-agent/agent-common/src/main/java/org/apache/inlong/agent/db/BerkeleyDbImp.java

@@ -141,14 +141,12 @@ public KeyValueEntity get(String key) {
         return primaryIndex.get(key);
     }
 
-
     @Override
     public CommandEntity getCommand(String commandId) {
         requireNonNull(commandId);
         return commandPrimaryIndex.get(commandId);
     }
 
-
     @Override
     public CommandEntity putCommand(CommandEntity entity) {
         requireNonNull(entity);

inlong-agent/agent-common/src/main/java/org/apache/inlong/agent/db/CommandDb.java

@@ -49,7 +49,6 @@ public List<CommandEntity> getUnackedCommands() {
         return db.searchCommands(false);
     }
 
-
     /**
      * save normal command result for trigger
      * @param profile

inlong-agent/agent-common/src/main/java/org/apache/inlong/agent/db/CommandEntity.java

@@ -25,7 +25,6 @@
 import lombok.Data;
 import lombok.NoArgsConstructor;
 
-
 @Entity(version = 1)
 @Data
 @AllArgsConstructor
@@ -39,7 +38,6 @@ public class CommandEntity {
     private String taskId;
     private String deliveryTime;
 
-
     public static String generateCommanid(String taskId, int opType) {
         return taskId + opType;
     }

inlong-agent/agent-common/src/main/java/org/apache/inlong/agent/db/Db.java

@@ -26,7 +26,6 @@
  */
 public interface Db extends Closeable {
 
-
     abstract KeyValueEntity get(String key);
 
     /**

inlong-agent/agent-common/src/main/java/org/apache/inlong/agent/db/JobProfileDb.java

@@ -150,7 +150,6 @@ public JobProfile getJob(StateSearchKey stateSearchKey) {
         return null;
     }
 
-
     /**
      * get job reading specific file
      * @param fileName

inlong-agent/agent-common/src/main/java/org/apache/inlong/agent/db/LocalProfile.java

@@ -15,7 +15,6 @@
  * limitations under the License.
  */
 
-
 package org.apache.inlong.agent.db;
 
 import java.nio.file.Files;

inlong-agent/agent-common/src/main/java/org/apache/inlong/agent/db/TriggerProfileDb.java

@@ -17,7 +17,6 @@
 
 package org.apache.inlong.agent.db;
 
-
 import java.util.ArrayList;
 import java.util.List;
 import org.apache.inlong.agent.conf.TriggerProfile;

inlong-agent/agent-common/src/main/java/org/apache/inlong/agent/message/ProxyMessage.java

@@ -32,7 +32,6 @@ public class ProxyMessage implements Message {
     private final String bid;
     private final String tid;
 
-
     public ProxyMessage(byte[] body, Map<String, String> header) {
         this.body = body;
         this.header = header;

inlong-agent/agent-common/src/main/java/org/apache/inlong/agent/metrics/AgentDynamicMBean.java

@@ -67,7 +67,6 @@ private void formatSnapshotList(Object source) {
         }
     }
 
-
     private MBeanInfo metricsMetaToInfo() {
         // overwrite name, desc from MetricsMeta if not null.
         String name = this.module == null ? metricsMeta.getName() : this.module;

inlong-agent/agent-common/src/main/java/org/apache/inlong/agent/metrics/MetricsRegister.java

@@ -81,7 +81,6 @@ public static void register(String module, String aspect, String desc, Object so
         }
     }
 
-
     /**
      * handle class level annotation
      */
@@ -95,7 +94,6 @@ private static MetricsMeta handleClassAnnotation(Object source,
         return null;
     }
 
-
     private static boolean initFieldByType(Object source, Field field) {
         try {
             if (field.getType() == CounterInt.class) {

inlong-agent/agent-common/src/main/java/org/apache/inlong/agent/metrics/gauge/Gauge.java

@@ -17,7 +17,6 @@
 
 package org.apache.inlong.agent.metrics.gauge;
 
-
 import org.apache.inlong.agent.metrics.MutableMetric;
 
 public interface Gauge<T> extends MutableMetric {

inlong-agent/agent-common/src/main/java/org/apache/inlong/agent/plugin/Channel.java

@@ -24,7 +24,6 @@
  */
 public interface Channel extends Stage {
 
-
     /**
      * write message
      *

inlong-agent/agent-common/src/main/java/org/apache/inlong/agent/plugin/Sink.java

@@ -29,7 +29,6 @@ public interface Sink extends Stage {
      */
     void write(Message message);
 
-
     /**
      * set source file name where the message is generated
      * @param sourceFileName

inlong-agent/agent-common/src/main/java/org/apache/inlong/agent/state/AbstractStateWrapper.java

@@ -40,7 +40,6 @@ public AbstractStateWrapper() {
      */
     public abstract void addCallbacks();
 
-
     public AbstractStateWrapper addCallback(State begin, State end, StateCallback callback) {
         callBacks.put(new ImmutablePair<>(begin, end), callback);
         return this;

inlong-agent/agent-common/src/main/java/org/apache/inlong/agent/state/StateTransferException.java

@@ -17,7 +17,6 @@
 
 package org.apache.inlong.agent.state;
 
-
 public class StateTransferException extends RuntimeException {
 
     public StateTransferException(State begin, State end) {

inlong-agent/agent-common/src/main/java/org/apache/inlong/agent/utils/AgentUtils.java

@@ -67,7 +67,6 @@ public class AgentUtils {
     public static final String HOUR_LOW_CASE = "h";
     public static final String MINUTE = "m";
 
-
     /**
      * get md5 of file.
      * @param file - file name
@@ -227,7 +226,6 @@ public static String formatCurrentTimeWithOffset(String formatter, int day, int
         return DateTimeFormatter.ofPattern(formatter).withLocale(Locale.getDefault()).format(zoned);
     }
 
-
     public static String formatCurrentTimeWithoutOffset(String formatter) {
         ZonedDateTime zoned = ZonedDateTime.now().plusDays(0).plusHours(0).plusMinutes(0);
         return DateTimeFormatter.ofPattern(formatter).withLocale(Locale.getDefault()).format(zoned);
@@ -303,7 +301,6 @@ public static Map<String, String> getAdditionAttr(String additionStr) {
         return mValueAttrs.getRight();
     }
 
-
     /**
      * get m value in additionStr
      * @param addictiveAttr
@@ -356,8 +353,4 @@ private static long parseTimeToMillSec(String time, String pattern) {
         return System.currentTimeMillis();
     }
 
-
-
-
-
 }

inlong-agent/agent-common/src/main/java/org/apache/inlong/agent/utils/ByteUtil.java

@@ -15,7 +15,6 @@
  * limitations under the License.
  */
 
-
 package org.apache.inlong.agent.utils;
 
 import java.util.ArrayList;

inlong-agent/agent-common/src/test/java/org/apache/inlong/agent/common/TestAgentUtils.java

@@ -69,7 +69,6 @@ public void testDateFormatterWithOffset() {
         LOGGER.info("agent time is {}", time);
     }
 
-
     @Test
     public void testParseAddictiveStr() {
         String addStr = "m=10&__addcol1__worldid=&t=1";

inlong-agent/agent-common/src/test/java/org/apache/inlong/agent/db/TestBerkeleyDBImp.java

@@ -24,7 +24,6 @@
 import org.junit.BeforeClass;
 import org.junit.Test;
 
-
 public class TestBerkeleyDBImp {
 
     private static BerkeleyDbImp db;
@@ -77,7 +76,6 @@ public void testKeyValueDB() {
 
     }
 
-
     @Test
     public void testCommandDb() {
         CommandEntity commandEntity = new CommandEntity("1", 0, false, "1", "");
@@ -123,7 +121,6 @@ public void testDeleteItem() {
         Assert.assertNull(entityResult);
     }
 
-
     @Test
     public void testFileNameSearch() {
         KeyValueEntity entity = new KeyValueEntity("searchKey1", "searchResult1", "test");

inlong-agent/agent-core/src/main/java/org/apache/inlong/agent/core/AgentManager.java

@@ -17,7 +17,6 @@
 
 package org.apache.inlong.agent.core;
 
-
 import static org.apache.inlong.agent.constants.AgentConstants.AGENT_CONF_PARENT;
 import static org.apache.inlong.agent.constants.AgentConstants.DEFAULT_AGENT_CONF_PARENT;
 import static org.apache.inlong.agent.constants.JobConstants.JOB_TRIGGER;
@@ -58,8 +57,6 @@ public class AgentManager extends AbstractDaemon {
     // jetty for config operations via http.
     private ConfigJetty configJetty;
 
-
-
     private final ProfileFetcher fetcher;
     private final AgentConfiguration conf;
     private final Db db;

inlong-agent/agent-core/src/main/java/org/apache/inlong/agent/core/job/Job.java

@@ -17,7 +17,6 @@
 
 package org.apache.inlong.agent.core.job;
 
-
 import java.util.ArrayList;
 import java.util.List;
 import org.apache.inlong.agent.conf.JobProfile;

inlong-agent/agent-core/src/main/java/org/apache/inlong/agent/core/job/JobManager.java

@@ -17,7 +17,6 @@
 
 package org.apache.inlong.agent.core.job;
 
-
 import static org.apache.inlong.agent.constants.AgentConstants.DEFAULT_JOB_DB_CACHE_CHECK_INTERVAL;
 import static org.apache.inlong.agent.constants.AgentConstants.DEFAULT_JOB_DB_CACHE_TIME;
 import static org.apache.inlong.agent.constants.AgentConstants.JOB_DB_CACHE_CHECK_INTERVAL;

inlong-agent/agent-core/src/main/java/org/apache/inlong/agent/core/job/JobMetrics.java

@@ -15,7 +15,6 @@
  * limitations under the License.
  */
 
-
 package org.apache.inlong.agent.core.job;
 
 import java.util.concurrent.atomic.AtomicBoolean;

inlong-agent/agent-core/src/main/java/org/apache/inlong/agent/core/task/Task.java

@@ -22,7 +22,6 @@
 import org.apache.inlong.agent.plugin.Reader;
 import org.apache.inlong.agent.plugin.Sink;
 
-
 /**
  * task meta definition which contains reader -> channel -> sink and job config information
  */

inlong-agent/agent-core/src/main/java/org/apache/inlong/agent/core/task/TaskPositionManager.java

@@ -105,7 +105,6 @@ private Runnable taskPositionFlushThread() {
         };
     }
 
-
     private void flushJobProfile(String jobId, JobProfile jobProfile) {
         jobTaskPositionMap.get(jobId).forEach(
             (fileName, position) -> jobProfile.setLong(fileName + POSITION_SUFFIX, position)
@@ -137,7 +136,6 @@ public void updateFileSinkPosition(String jobInstanceId, String sourceFilePath,
         filePosition.put(sourceFilePath, beforePosition + size);
     }
 
-
     public ConcurrentHashMap<String, Long> getTaskPositionMap(String jobId) {
         return jobTaskPositionMap.get(jobId);
     }

inlong-agent/agent-core/src/main/java/org/apache/inlong/agent/core/task/TaskWrapper.java

@@ -17,7 +17,6 @@
 
 package org.apache.inlong.agent.core.task;
 
-
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.SynchronousQueue;
@@ -177,7 +176,6 @@ public void addCallbacks() {
         });
     }
 
-
     @Override
     public void run() {
         try {