[CALCITE-5534] Add userAgent JDBC param

core/src/main/java/org/apache/calcite/avatica/BuiltInConnectionProperty.java

@@ -91,7 +91,10 @@ public enum BuiltInConnectionProperty implements ConnectionProperty {
   TRANSPARENT_RECONNECTION("transparent_reconnection", Type.BOOLEAN, Boolean.FALSE, false),
 
   /** Number of rows to fetch per call. */
-  FETCH_SIZE("fetch_size", Type.NUMBER, AvaticaStatement.DEFAULT_FETCH_SIZE, false);
+  FETCH_SIZE("fetch_size", Type.NUMBER, AvaticaStatement.DEFAULT_FETCH_SIZE, false),
+
+  /** User-Agent header to identify requests performed by a particular application **/
+  USER_AGENT("userAgent", Type.STRING, "", false);
 
   private final String camelName;
   private final Type type;

core/src/main/java/org/apache/calcite/avatica/ConnectionConfig.java

@@ -66,6 +66,8 @@ public interface ConnectionConfig {
   boolean transparentReconnectionEnabled();
   /** @see BuiltInConnectionProperty#FETCH_SIZE */
   int fetchSize();
+  /** @see BuiltInConnectionProperty#USER_AGENT */
+  String userAgent();
 }
 
 // End ConnectionConfig.java

core/src/main/java/org/apache/calcite/avatica/ConnectionConfigImpl.java

@@ -137,6 +137,10 @@ public int fetchSize() {
     return BuiltInConnectionProperty.FETCH_SIZE.wrap(properties).getInt();
   }
 
+  public String userAgent() {
+    return BuiltInConnectionProperty.USER_AGENT.wrap(properties).getString();
+  }
+
   /** Converts a {@link Properties} object containing (name, value)
    * pairs into a map whose keys are
    * {@link org.apache.calcite.avatica.InternalProperty} objects.

core/src/main/java/org/apache/calcite/avatica/remote/AvaticaCommonsHttpClientImpl.java

@@ -86,6 +86,7 @@ public class AvaticaCommonsHttpClientImpl implements AvaticaHttpClient, HttpClie
   protected CredentialsProvider credentialsProvider = null;
   protected Lookup<AuthSchemeFactory> authRegistry = null;
   protected Object userToken;
+  protected String userAgent;
 
   public AvaticaCommonsHttpClientImpl(URL url) {
     this.uri = toURI(Objects.requireNonNull(url));
@@ -119,6 +120,10 @@ protected void initializeClient(PoolingHttpClientConnectionManager pool) {
       HttpPost post = new HttpPost(uri);
       post.setEntity(entity);
 
+      if (null != userAgent) {
+        post.addHeader("User-Agent", userAgent);
+      }
+
       try (CloseableHttpResponse response = execute(post, context)) {
         final int statusCode = response.getCode();
         if (HttpURLConnection.HTTP_OK == statusCode
@@ -145,6 +150,11 @@ protected void initializeClient(PoolingHttpClientConnectionManager pool) {
     }
   }
 
+  @Override
+  public void setUserAgent(String userAgent) {
+    this.userAgent = userAgent;
+  }
+
   // Visible for testing
   CloseableHttpResponse execute(HttpPost post, HttpClientContext context)
       throws IOException, ClientProtocolException {

core/src/main/java/org/apache/calcite/avatica/remote/AvaticaHttpClient.java

@@ -29,6 +29,14 @@ public interface AvaticaHttpClient {
    */
   byte[] send(byte[] request);
 
+  /**
+   * Sets the "User-Agent" HTTP header for all request to the Avatica server.
+   *
+   * @param userAgent The "User-Agent" to use. Configurable via
+   * {@link org.apache.calcite.avatica.BuiltInConnectionProperty#USER_AGENT}
+   */
+  void setUserAgent(String userAgent);
+
 }
 
 // End AvaticaHttpClient.java

core/src/main/java/org/apache/calcite/avatica/remote/AvaticaHttpClientFactoryImpl.java

@@ -134,6 +134,10 @@ public static AvaticaHttpClientFactoryImpl getInstance() {
       client = new DoAsAvaticaHttpClient(client, kerberosUtil);
     }
 
+    if (!config.userAgent().isEmpty()) {
+      client.setUserAgent(config.userAgent());
+    }
+
     return client;
   }
 

core/src/main/java/org/apache/calcite/avatica/remote/AvaticaHttpClientImpl.java

@@ -30,6 +30,7 @@
  */
 public class AvaticaHttpClientImpl implements AvaticaHttpClient {
   protected final URL url;
+  protected String userAgent;
 
   public AvaticaHttpClientImpl(URL url) {
     this.url = url;
@@ -43,6 +44,11 @@ public byte[] send(byte[] request) {
         connection.setRequestMethod("POST");
         connection.setDoInput(true);
         connection.setDoOutput(true);
+
+        if (null != userAgent) {
+          connection.setRequestProperty("User-Agent", userAgent);
+        }
+
         try (DataOutputStream wr = new DataOutputStream(connection.getOutputStream())) {
           wr.write(request);
           wr.flush();
@@ -69,6 +75,11 @@ public byte[] send(byte[] request) {
     }
   }
 
+  @Override
+  public void setUserAgent(String userAgent) {
+    this.userAgent = userAgent;
+  }
+
   HttpURLConnection openConnection() throws IOException {
     return (HttpURLConnection) url.openConnection();
   }

core/src/main/java/org/apache/calcite/avatica/remote/DoAsAvaticaHttpClient.java

@@ -40,6 +40,11 @@ public DoAsAvaticaHttpClient(AvaticaHttpClient wrapped, KerberosConnection kerbe
       }
     });
   }
+
+  @Override
+  public void setUserAgent(String userAgent) {
+    wrapped.setUserAgent(userAgent);
+  }
 }
 
 // End DoAsAvaticaHttpClient.java

server/src/test/java/org/apache/calcite/avatica/remote/AlternatingRemoteMetaTest.java

@@ -124,6 +124,9 @@ public byte[] send(byte[] request) {
       return client.send(request);
     }
 
+    @Override
+    public void setUserAgent(String userAgent) {}
+
   }
 
   /**