Expose X-ClickHouse-Server-Display-Name header via client-v2 API

client-v2/src/main/java/com/clickhouse/client/api/Client.java

@@ -1338,7 +1338,7 @@ public CompletableFuture<InsertResponse> insert(String tableName, List<?> data,
                     String queryId =  HttpAPIClientHelper.getHeaderVal(httpResponse.getFirstHeader(ClickHouseHttpProto.HEADER_QUERY_ID), requestSettings.getQueryId(), String::valueOf);
                     metrics.operationComplete();
                     metrics.setQueryId(queryId);
-                    return new InsertResponse(metrics);
+                    return new InsertResponse(metrics, HttpAPIClientHelper.collectResponseHeaders(httpResponse));
                 } catch (Exception e) {
                     String msg = requestExMsg("Insert", (i + 1), durationSince(startTime).toMillis(), requestSettings.getQueryId());
                     lastException = httpClientHelper.wrapException(msg, e, requestSettings.getQueryId());
@@ -1545,7 +1545,7 @@ public CompletableFuture<InsertResponse> insert(String tableName,
                     String queryId =  HttpAPIClientHelper.getHeaderVal(httpResponse.getFirstHeader(ClickHouseHttpProto.HEADER_QUERY_ID), requestSettings.getQueryId(), String::valueOf);
                     metrics.operationComplete();
                     metrics.setQueryId(queryId);
-                    return new InsertResponse(metrics);
+                    return new InsertResponse(metrics, HttpAPIClientHelper.collectResponseHeaders(httpResponse));
                 } catch (Exception e) {
                     String msg = requestExMsg("Insert", (i + 1), durationSince(startTime).toMillis(), requestSettings.getQueryId());
                     lastException = httpClientHelper.wrapException(msg, e, requestSettings.getQueryId());
@@ -1684,7 +1684,8 @@ public CompletableFuture<QueryResponse> query(String sqlQuery, Map<String, Objec
                             responseFormat = ClickHouseFormat.valueOf(formatHeader.getValue());
                         }
 
-                        return new QueryResponse(httpResponse, responseFormat, requestSettings, metrics);
+                        return new QueryResponse(httpResponse, responseFormat, requestSettings, metrics,
+                                HttpAPIClientHelper.collectResponseHeaders(httpResponse));
 
                     } catch (Exception e) {
                         HttpAPIClientHelper.closeQuietly(httpResponse);

client-v2/src/main/java/com/clickhouse/client/api/command/CommandResponse.java

@@ -5,6 +5,8 @@
 import com.clickhouse.client.api.metrics.ServerMetrics;
 import com.clickhouse.client.api.query.QueryResponse;
 
+import java.util.Map;
+
 public class CommandResponse implements AutoCloseable {
 
     private final QueryResponse response;
@@ -72,6 +74,25 @@ public long getServerTime() {
         return response.getServerTime();
     }
 
+    /**
+     * Returns the value of {@code X-ClickHouse-Server-Display-Name} response header.
+     *
+     * @return server display name or {@code null} if not present
+     */
+    public String getServerDisplayName() {
+        return response.getServerDisplayName();
+    }
+
+    /**
+     * Returns all collected response headers as an unmodifiable map.
+     * Only whitelisted ClickHouse headers are included.
+     *
+     * @return map of header name to header value
+     */
+    public Map<String, String> getResponseHeaders() {
+        return response.getResponseHeaders();
+    }
+
     @Override
     public void close() throws Exception {
         response.close();

client-v2/src/main/java/com/clickhouse/client/api/insert/InsertResponse.java

@@ -1,13 +1,23 @@
 package com.clickhouse.client.api.insert;
 
+import com.clickhouse.client.api.http.ClickHouseHttpProto;
 import com.clickhouse.client.api.metrics.OperationMetrics;
 import com.clickhouse.client.api.metrics.ServerMetrics;
 
+import java.util.Collections;
+import java.util.Map;
+
 public class InsertResponse implements AutoCloseable {
     private OperationMetrics operationMetrics;
+    private final Map<String, String> responseHeaders;
 
     public InsertResponse(OperationMetrics metrics) {
+        this(metrics, Collections.emptyMap());
+    }
+
+    public InsertResponse(OperationMetrics metrics, Map<String, String> responseHeaders) {
         this.operationMetrics = metrics;
+        this.responseHeaders = responseHeaders;
     }
 
     @Override
@@ -78,4 +88,23 @@ public long getResultRows() {
     public String getQueryId() {
         return operationMetrics.getQueryId();
     }
+
+    /**
+     * Returns the value of {@code X-ClickHouse-Server-Display-Name} response header.
+     *
+     * @return server display name or {@code null} if not present
+     */
+    public String getServerDisplayName() {
+        return responseHeaders.get(ClickHouseHttpProto.HEADER_SRV_DISPLAY_NAME);
+    }
+
+    /**
+     * Returns all collected response headers as an unmodifiable map.
+     * Only whitelisted ClickHouse headers are included.
+     *
+     * @return map of header name to header value
+     */
+    public Map<String, String> getResponseHeaders() {
+        return responseHeaders;
+    }
 }

client-v2/src/main/java/com/clickhouse/client/api/internal/HttpAPIClientHelper.java

@@ -95,6 +95,8 @@
 import java.util.Objects;
 import java.util.Optional;
 import java.util.Properties;
+import java.util.Arrays;
+import java.util.HashMap;
 import java.util.Set;
 import java.util.concurrent.ConcurrentLinkedQueue;
 import java.util.concurrent.TimeUnit;
@@ -752,6 +754,31 @@ public static int getHeaderInt(Header header, int defaultValue) {
         return getHeaderVal(header, defaultValue, Integer::parseInt);
     }
 
+    private static final Set<String> RESPONSE_HEADER_WHITELIST = new HashSet<>(Arrays.asList(
+            ClickHouseHttpProto.HEADER_QUERY_ID,
+            ClickHouseHttpProto.HEADER_SRV_SUMMARY,
+            ClickHouseHttpProto.HEADER_SRV_DISPLAY_NAME,
+            ClickHouseHttpProto.HEADER_DATABASE,
+            ClickHouseHttpProto.HEADER_DB_USER
+    ));
+
+    /**
+     * Collects whitelisted response headers from an HTTP response into a map.
+     *
+     * @param response the HTTP response
+     * @return unmodifiable map of header name to header value for whitelisted headers present in the response
+     */
+    public static Map<String, String> collectResponseHeaders(ClassicHttpResponse response) {
+        Map<String, String> headers = new HashMap<>();
+        for (String name : RESPONSE_HEADER_WHITELIST) {
+            Header header = response.getFirstHeader(name);
+            if (header != null) {
+                headers.put(name, header.getValue());
+            }
+        }
+        return Collections.unmodifiableMap(headers);
+    }
+
     public static String getHeaderVal(Header header, String defaultValue) {
         return getHeaderVal(header, defaultValue, Function.identity());
     }

client-v2/src/main/java/com/clickhouse/client/api/query/QueryResponse.java

@@ -10,6 +10,8 @@
 import org.apache.hc.core5.http.Header;
 
 import java.io.InputStream;
+import java.util.Collections;
+import java.util.Map;
 import java.util.TimeZone;
 
 /**
@@ -35,12 +37,20 @@ public class QueryResponse implements AutoCloseable {
 
     private ClassicHttpResponse httpResponse;
 
+    private final Map<String, String> responseHeaders;
+
     public QueryResponse(ClassicHttpResponse response, ClickHouseFormat format, QuerySettings settings,
                          OperationMetrics operationMetrics) {
+        this(response, format, settings, operationMetrics, Collections.emptyMap());
+    }
+
+    public QueryResponse(ClassicHttpResponse response, ClickHouseFormat format, QuerySettings settings,
+                         OperationMetrics operationMetrics, Map<String, String> responseHeaders) {
         this.httpResponse = response;
         this.format = format;
         this.operationMetrics = operationMetrics;
         this.settings = settings;
+        this.responseHeaders = responseHeaders;
 
         Header tzHeader = response.getFirstHeader(ClickHouseHttpProto.HEADER_TIMEZONE);
         if (tzHeader != null) {
@@ -150,6 +160,25 @@ public String getQueryId() {
         return operationMetrics.getQueryId();
     }
 
+    /**
+     * Returns the value of {@code X-ClickHouse-Server-Display-Name} response header.
+     *
+     * @return server display name or {@code null} if not present
+     */
+    public String getServerDisplayName() {
+        return responseHeaders.get(ClickHouseHttpProto.HEADER_SRV_DISPLAY_NAME);
+    }
+
+    /**
+     * Returns all collected response headers as an unmodifiable map.
+     * Only whitelisted ClickHouse headers are included.
+     *
+     * @return map of header name to header value
+     */
+    public Map<String, String> getResponseHeaders() {
+        return responseHeaders;
+    }
+
     public TimeZone getTimeZone() {
         return settings.getOption(ClientConfigProperties.SERVER_TIMEZONE.getKey()) == null
                 ? null