PR feedback: prefer emptyMap, no wildcard imports

Author: Ray Mattingly

hbase-client/src/main/java/org/apache/hadoop/hbase/client/AsyncConnectionImpl.java

@@ -31,6 +31,7 @@
 import io.opentelemetry.api.trace.Span;
 import java.io.IOException;
 import java.net.SocketAddress;
+import java.util.Collections;
 import java.util.Map;
 import java.util.Optional;
 import java.util.concurrent.CompletableFuture;
@@ -128,7 +129,7 @@ public class AsyncConnectionImpl implements AsyncConnection {
 
   public AsyncConnectionImpl(Configuration conf, ConnectionRegistry registry, String clusterId,
     SocketAddress localAddress, User user) {
-    this(conf, registry, clusterId, localAddress, user, null);
+    this(conf, registry, clusterId, localAddress, user, Collections.emptyMap());
   }
 
   public AsyncConnectionImpl(Configuration conf, ConnectionRegistry registry, String clusterId,

hbase-client/src/main/java/org/apache/hadoop/hbase/client/ConnectionFactory.java

@@ -22,6 +22,7 @@
 import java.io.IOException;
 import java.lang.reflect.Constructor;
 import java.security.PrivilegedExceptionAction;
+import java.util.Collections;
 import java.util.Map;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutorService;
@@ -217,7 +218,7 @@ public static Connection createConnection(Configuration conf, User user) throws
    */
   public static Connection createConnection(Configuration conf, ExecutorService pool,
     final User user) throws IOException {
-    return createConnection(conf, pool, user, null);
+    return createConnection(conf, pool, user, Collections.emptyMap());
   }
 
   /**

hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/BlockingRpcClient.java

@@ -19,6 +19,7 @@
 
 import java.io.IOException;
 import java.net.SocketAddress;
+import java.util.Collections;
 import java.util.Map;
 import javax.net.SocketFactory;
 import org.apache.hadoop.conf.Configuration;
@@ -42,7 +43,7 @@ public class BlockingRpcClient extends AbstractRpcClient<BlockingRpcConnection>
    * SocketFactory
    */
   BlockingRpcClient(Configuration conf) {
-    this(conf, HConstants.CLUSTER_ID_DEFAULT, null, null, null);
+    this(conf, HConstants.CLUSTER_ID_DEFAULT, null, null, Collections.emptyMap());
   }
 
   /**

hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/DelegatingHBaseRpcController.java

@@ -18,6 +18,7 @@
 package org.apache.hadoop.hbase.ipc;
 
 import java.io.IOException;
+import java.util.Collections;
 import java.util.Map;
 import org.apache.hadoop.hbase.CellScanner;
 import org.apache.hadoop.hbase.TableName;
@@ -115,7 +116,7 @@ public boolean hasCallTimeout() {
 
   @Override
   public Map<String, byte[]> getAttributes() {
-    return null;
+    return Collections.emptyMap();
   }
 
   @Override

hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/HBaseRpcControllerImpl.java

@@ -19,6 +19,7 @@
 
 import java.io.IOException;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 import org.apache.hadoop.hbase.CellScannable;
@@ -169,7 +170,7 @@ public boolean hasCallTimeout() {
 
   @Override
   public Map<String, byte[]> getAttributes() {
-    return null;
+    return Collections.emptyMap();
   }
 
   @Override

hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/NettyRpcClient.java

@@ -19,6 +19,7 @@
 
 import java.io.IOException;
 import java.net.SocketAddress;
+import java.util.Collections;
 import java.util.Map;
 import java.util.concurrent.atomic.AtomicReference;
 import org.apache.hadoop.conf.Configuration;
@@ -56,7 +57,7 @@ public class NettyRpcClient extends AbstractRpcClient<NettyRpcConnection> {
 
   public NettyRpcClient(Configuration configuration, String clusterId, SocketAddress localAddress,
     MetricsConnection metrics) {
-    this(configuration, clusterId, localAddress, metrics, null);
+    this(configuration, clusterId, localAddress, metrics, Collections.emptyMap());
   }
 
   public NettyRpcClient(Configuration configuration, String clusterId, SocketAddress localAddress,
@@ -81,7 +82,7 @@ public NettyRpcClient(Configuration configuration, String clusterId, SocketAddre
 
   /** Used in test only. */
   public NettyRpcClient(Configuration configuration) {
-    this(configuration, HConstants.CLUSTER_ID_DEFAULT, null, null, null);
+    this(configuration, HConstants.CLUSTER_ID_DEFAULT, null, null, Collections.emptyMap());
   }
 
   @Override

hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/RpcClientFactory.java

@@ -18,6 +18,7 @@
 package org.apache.hadoop.hbase.ipc;
 
 import java.net.SocketAddress;
+import java.util.Collections;
 import java.util.Map;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.hbase.client.MetricsConnection;
@@ -60,7 +61,7 @@ public static RpcClient createClient(Configuration conf, String clusterId) {
    */
   public static RpcClient createClient(Configuration conf, String clusterId,
     MetricsConnection metrics) {
-    return createClient(conf, clusterId, null, metrics, null);
+    return createClient(conf, clusterId, null, metrics, Collections.emptyMap());
   }
 
   private static String getRpcClientClass(Configuration conf) {

hbase-server/src/main/java/org/apache/hadoop/hbase/client/AsyncClusterConnectionImpl.java

@@ -18,6 +18,7 @@
 package org.apache.hadoop.hbase.client;
 
 import java.net.SocketAddress;
+import java.util.Collections;
 import java.util.List;
 import java.util.concurrent.CompletableFuture;
 import java.util.stream.Collectors;
@@ -59,7 +60,7 @@ class AsyncClusterConnectionImpl extends AsyncConnectionImpl implements AsyncClu
 
   public AsyncClusterConnectionImpl(Configuration conf, ConnectionRegistry registry,
     String clusterId, SocketAddress localAddress, User user) {
-    super(conf, registry, clusterId, localAddress, user, null);
+    super(conf, registry, clusterId, localAddress, user, Collections.emptyMap());
   }
 
   @Override

hbase-server/src/main/java/org/apache/hadoop/hbase/ipc/ServerCall.java

@@ -17,8 +17,6 @@
  */
 package org.apache.hadoop.hbase.ipc;
 
-import static org.apache.hadoop.hbase.shaded.protobuf.generated.RPCProtos.*;
-
 import io.opentelemetry.api.trace.Span;
 import io.opentelemetry.api.trace.StatusCode;
 import io.opentelemetry.context.Scope;
@@ -51,6 +49,7 @@
 
 import org.apache.hadoop.hbase.shaded.protobuf.ProtobufUtil;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.HBaseProtos.VersionInfo;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.RPCProtos;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.RPCProtos.CellBlockMeta;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.RPCProtos.ExceptionResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.RPCProtos.RequestHeader;
@@ -210,7 +209,7 @@ public RequestHeader getHeader() {
   }
 
   @Override
-  public ConnectionHeader getConnectionHeader() {
+  public RPCProtos.ConnectionHeader getConnectionHeader() {
     return this.connection.connectionHeader;
   }