fix(checkstyle): resolve all remaining violations across connector/storage/sdk modules

- Fix 115 real violations in 30+ files (EmptyLineSeparator, NeedBraces,
  AvoidStarImport, EmptyCatchBlock, VariableDeclarationUsageDistance,
  LocalVariableName, OverloadMethodsDeclarationOrder, Indentation, non-ASCII)
- Expand wildcard imports to explicit types (pulsar/rabbitmq/redis/s3/jdbc)
- CloudEventsClient: rename empty-catch var to 'expected'; reorder unsubscribe overloads
- Kafka IT: replace System.out.println with @slf4j logger; final vars
- Fix jdbc build.gradle: exclude flat ANTLR generated sources from checkstyle
  by absolute path (package-path excludes cannot match srcDir-relative flat files),
  eliminating 30k+ generated-code warnings

Verified: full checkstyleMain + checkstyleTest BUILD SUCCESSFUL on JDK 21.

Author: qqeasonchen

eventmesh-connector-plugin/eventmesh-connector-http/src/main/java/org/apache/eventmesh/connector/http/sink/HttpSinkConnector.java

@@ -30,10 +30,12 @@
 public class HttpSinkConnector implements SinkConnector {
 
     private String url;
+
     @Override
     public void init(Properties props) {
         url = props.getProperty("connector.url", "http://localhost:9090/sink");
     }
+
     @Override
     public void put(List<CloudEvent> events) {
         for (CloudEvent event : events) {
@@ -50,6 +52,7 @@ public void put(List<CloudEvent> events) {
             }
         }
     }
+
     @Override
     public void commit(List<CloudEvent> written) {
 

eventmesh-connector-plugin/eventmesh-connector-http/src/main/java/org/apache/eventmesh/connector/http/source/HttpSourceConnector.java

@@ -35,6 +35,7 @@ public class HttpSourceConnector implements SourceConnector {
 
     private java.util.concurrent.LinkedBlockingQueue<byte[]> buffer;
     private com.sun.net.httpserver.HttpServer server;
+
     @Override
     public void init(Properties props) {
         int port = Integer.parseInt(props.getProperty("connector.port", "8082"));
@@ -54,17 +55,21 @@ public void init(Properties props) {
             throw new RuntimeException(e);
         }
     }
+
     @Override
     public List<CloudEvent> poll() {
-        if (buffer == null)
+        if (buffer == null) {
             return Collections.emptyList();
+        }
         List<CloudEvent> out = new ArrayList<>();
         byte[] body;
-        while ((body = buffer.poll()) != null)
+        while ((body = buffer.poll()) != null) {
             out.add(CloudEventBuilder.v1().withId("http-" + System.nanoTime()).withSource(URI.create("http-webhook"))
                 .withType("http.request").withDataContentType("application/octet-stream").withData(body).build());
+        }
         return out;
     }
+
     @Override
     public void commit(CloudEvent lastPublished) {
 

eventmesh-connector-plugin/eventmesh-connector-jdbc/build.gradle

@@ -22,3 +22,11 @@ generateGrammarSource {
 tasks.named('packageSources') {
     dependsOn tasks.named('generateGrammarSource')
 }
+
+// ANTLR emits generated sources flat under build/generated-src/antlr/main (no package
+// sub-dirs), so the root project's package-path based checkstyle excludes cannot match
+// them. Strip that tree from checkstyle input here to avoid tens of thousands of
+// generated-code warnings failing the build.
+tasks.withType(Checkstyle).configureEach {
+    exclude { it.file.absolutePath.replace(File.separatorChar, (char) '/').contains('/build/generated-src/antlr/') }
+}

eventmesh-connector-plugin/eventmesh-connector-jdbc/src/main/java/org/apache/eventmesh/connector/jdbc/sink/JdbcSinkConnector.java

@@ -19,7 +19,9 @@
 
 import org.apache.eventmesh.connector.SinkConnector;
 
-import java.sql.*;
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.PreparedStatement;
 import java.util.List;
 import java.util.Properties;
 
@@ -33,6 +35,7 @@ public class JdbcSinkConnector implements SinkConnector {
     private Connection conn;
     private String insertSql;
     private Properties props;
+
     @Override
     public void init(Properties props) {
         this.props = props;
@@ -44,6 +47,7 @@ public void init(Properties props) {
             throw new RuntimeException(e);
         }
     }
+
     @Override
     public void put(List<CloudEvent> events) {
         try (PreparedStatement ps = conn.prepareStatement(insertSql)) {
@@ -57,6 +61,7 @@ public void put(List<CloudEvent> events) {
             throw new RuntimeException(e);
         }
     }
+
     @Override
     public void commit(List<CloudEvent> written) {
 

eventmesh-connector-plugin/eventmesh-connector-jdbc/src/main/java/org/apache/eventmesh/connector/jdbc/source/JdbcSourceConnector.java

@@ -21,7 +21,10 @@
 
 import java.net.URI;
 import java.nio.charset.StandardCharsets;
-import java.sql.*;
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.PreparedStatement;
+import java.sql.ResultSet;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Properties;
@@ -37,6 +40,7 @@ public class JdbcSourceConnector implements SourceConnector {
     private Connection conn;
     private String query;
     private String lastId;
+
     @Override
     public void init(Properties props) {
         String url = props.getProperty("connector.jdbcUrl", "jdbc:mysql://localhost:3306/test");
@@ -48,6 +52,7 @@ public void init(Properties props) {
             throw new RuntimeException(e);
         }
     }
+
     @Override
     public List<CloudEvent> poll() {
         List<CloudEvent> out = new ArrayList<>();
@@ -66,6 +71,7 @@ public List<CloudEvent> poll() {
         }
         return out;
     }
+
     @Override
     public void commit(CloudEvent lastPublished) {
 

eventmesh-connector-plugin/eventmesh-connector-knative/src/main/java/org/apache/eventmesh/connector/knative/sink/KnativeSinkConnector.java

@@ -31,11 +31,13 @@ public class KnativeSinkConnector implements SinkConnector {
 
     private String sinkUrl;
     private Properties props;
+
     @Override
     public void init(Properties props) {
         this.props = props;
         sinkUrl = props.getProperty("connector.sinkUrl", "http://localhost:8080/sink");
     }
+
     @Override
     public void put(List<CloudEvent> events) {
         for (CloudEvent event : events) {
@@ -52,6 +54,7 @@ public void put(List<CloudEvent> events) {
             }
         }
     }
+
     @Override
     public void commit(List<CloudEvent> written) {
 

eventmesh-connector-plugin/eventmesh-connector-knative/src/main/java/org/apache/eventmesh/connector/knative/source/KnativeSourceConnector.java

@@ -35,6 +35,7 @@ public class KnativeSourceConnector implements SourceConnector {
 
     private java.util.concurrent.LinkedBlockingQueue<byte[]> buffer;
     private com.sun.net.httpserver.HttpServer server;
+
     @Override
     public void init(Properties props) {
         int port = Integer.parseInt(props.getProperty("connector.port", "8080"));
@@ -54,17 +55,21 @@ public void init(Properties props) {
             throw new RuntimeException(e);
         }
     }
+
     @Override
     public List<CloudEvent> poll() {
-        if (buffer == null)
+        if (buffer == null) {
             return Collections.emptyList();
+        }
         List<CloudEvent> out = new ArrayList<>();
         byte[] body;
-        while ((body = buffer.poll()) != null)
+        while ((body = buffer.poll()) != null) {
             out.add(CloudEventBuilder.v1().withId("knative-" + System.nanoTime()).withSource(URI.create("knative"))
                 .withType("knative.event").withDataContentType("application/octet-stream").withData(body).build());
+        }
         return out;
     }
+
     @Override
     public void commit(CloudEvent lastPublished) {
 

eventmesh-connector-plugin/eventmesh-connector-lark/src/main/java/org/apache/eventmesh/connector/lark/sink/LarkSinkConnector.java

@@ -30,10 +30,12 @@
 public class LarkSinkConnector implements SinkConnector {
 
     private String webhookUrl;
+
     @Override
     public void init(Properties props) {
         webhookUrl = props.getProperty("connector.webhookUrl", "");
     }
+
     @Override
     public void put(List<CloudEvent> events) {
         for (CloudEvent event : events) {
@@ -50,6 +52,7 @@ public void put(List<CloudEvent> events) {
             }
         }
     }
+
     @Override
     public void commit(List<CloudEvent> written) {
 

eventmesh-connector-plugin/eventmesh-connector-mongodb/src/main/java/org/apache/eventmesh/connector/mongodb/sink/MongodbSinkConnector.java

@@ -36,6 +36,7 @@ public class MongodbSinkConnector implements SinkConnector {
 
     private com.mongodb.client.MongoCollection<Document> collection;
     private Properties props;
+
     @Override
     public void init(Properties props) {
         this.props = props;
@@ -44,13 +45,15 @@ public void init(Properties props) {
         String coll = props.getProperty("connector.collection", "sink");
         collection = MongoClients.create(uri).getDatabase(db).getCollection(coll);
     }
+
     @Override
     public void put(List<CloudEvent> events) {
         for (CloudEvent event : events) {
             byte[] data = event.getData() != null ? event.getData().toBytes() : new byte[0];
             collection.insertOne(Document.parse(new String(data, StandardCharsets.UTF_8)));
         }
     }
+
     @Override
     public void commit(List<CloudEvent> written) {
 

eventmesh-connector-plugin/eventmesh-connector-mongodb/src/main/java/org/apache/eventmesh/connector/mongodb/source/MongodbSourceConnector.java

@@ -41,6 +41,7 @@ public class MongodbSourceConnector implements SourceConnector {
     private MongoClient client;
     private com.mongodb.client.MongoCollection<Document> collection;
     private com.mongodb.client.ChangeStreamIterable<Document> changeStream;
+
     @Override
     public void init(Properties props) {
         String uri = props.getProperty("connector.mongoUri", "mongodb://localhost:27017");
@@ -50,18 +51,21 @@ public void init(Properties props) {
         collection = client.getDatabase(db).getCollection(coll);
         changeStream = collection.watch();
     }
+
     @Override
     public List<CloudEvent> poll() {
         List<CloudEvent> out = new ArrayList<>();
         try {
             com.mongodb.client.MongoChangeStreamCursor<com.mongodb.client.model.changestream.ChangeStreamDocument<Document>> cursor =
                 changeStream.cursor();
             for (int i = 0; i < 100; i++) {
-                if (!cursor.hasNext())
+                if (!cursor.hasNext()) {
                     break;
+                }
                 com.mongodb.client.model.changestream.ChangeStreamDocument<Document> csd = cursor.next();
-                if (csd == null || csd.getFullDocument() == null)
+                if (csd == null || csd.getFullDocument() == null) {
                     break;
+                }
                 Document doc = csd.getFullDocument();
                 out.add(CloudEventBuilder.v1().withId("mongo-" + doc.get("_id"))
                     .withSource(URI.create("mongodb")).withType("mongodb.change")
@@ -73,6 +77,7 @@ public List<CloudEvent> poll() {
         }
         return out;
     }
+
     @Override
     public void commit(CloudEvent lastPublished) {