GH-1319: Test hostname override builder configuration

Author: SwatiKumari250

flight/flight-sql-jdbc-core/src/test/java/org/apache/arrow/driver/jdbc/client/ArrowFlightSqlClientHandlerBuilderTest.java

@@ -137,6 +137,7 @@ public void testDefaults() {
     assertNull(builder.password);
     assertTrue(builder.useEncryption);
     assertFalse(builder.disableCertificateVerification);
+    assertNull(builder.hostnameOverride);
     assertNull(builder.trustStorePath);
     assertNull(builder.trustStorePassword);
     assertTrue(builder.useSystemTrustStore);
@@ -152,6 +153,18 @@ public void testDefaults() {
     assertNull(builder.driverVersion);
   }
 
+  @Test
+  public void testHostnameOverrideIsCopied() {
+    final String hostnameOverride = "flight.example.com";
+    final ArrowFlightSqlClientHandler.Builder rootBuilder =
+        new ArrowFlightSqlClientHandler.Builder().withHostnameOverride(hostnameOverride);
+
+    final ArrowFlightSqlClientHandler.Builder copiedBuilder =
+        new ArrowFlightSqlClientHandler.Builder(rootBuilder);
+
+    assertEquals(hostnameOverride, copiedBuilder.hostnameOverride);
+  }
+
   @Test
   public void testCatalog() {
     ArrowFlightSqlClientHandler.Builder rootBuilder = new ArrowFlightSqlClientHandler.Builder();