Remove unified flag usage, rely on host metadata

Port of Go SDK #1547. Removes HostType.UNIFIED and all runtime checks
of experimentalIsUnifiedHost. Host type is now determined solely from
URL pattern (accounts.* = ACCOUNTS, else WORKSPACE). Host metadata
resolution from /.well-known/databricks-config (added in PR 4) handles
populating accountId, workspaceId, and discoveryUrl automatically.

Key changes:
- getHostType(): no longer returns UNIFIED
- isAccountClient(): no longer throws for unified hosts
- getClientType(): simplified, no UNIFIED case
- fetchDefaultOidcEndpoints(): removed unified OIDC branch
- DatabricksCliCredentialsProvider: removed --experimental-is-unified-host
- AccountClient.getWorkspaceClient(): uses DNS zone matching (like Go SDK)
  to decide whether to reuse host or build deployment URL

Co-authored-by: Isaac

Author: hectorcast-db

databricks-sdk-java/src/main/java/com/databricks/sdk/AccountClient.java

@@ -30,18 +30,7 @@ public String authType() {
   List<String> buildHostArgs(String cliPath, DatabricksConfig config) {
     List<String> cmd =
         new ArrayList<>(Arrays.asList(cliPath, "auth", "token", "--host", config.getHost()));
-    if (config.getExperimentalIsUnifiedHost() != null && config.getExperimentalIsUnifiedHost()) {
-      // For unified hosts, pass account_id, workspace_id, and experimental flag
-      cmd.add("--experimental-is-unified-host");
-      if (config.getAccountId() != null) {
-        cmd.add("--account-id");
-        cmd.add(config.getAccountId());
-      }
-      if (config.getWorkspaceId() != null) {
-        cmd.add("--workspace-id");
-        cmd.add(config.getWorkspaceId());
-      }
-    } else if (config.getClientType() == ClientType.ACCOUNT) {
+    if (config.getClientType() == ClientType.ACCOUNT) {
       cmd.add("--account-id");
       cmd.add(config.getAccountId());
     }

databricks-sdk-java/src/main/java/com/databricks/sdk/core/DatabricksCliCredentialsProvider.java

@@ -270,11 +270,6 @@ public synchronized Map<String, String> authenticate() throws DatabricksExceptio
       }
       Map<String, String> headers = new HashMap<>(headerFactory.headers());
 
-      // For unified hosts with workspace operations, add the X-Databricks-Org-Id header
-      if (getHostType() == HostType.UNIFIED && workspaceId != null && !workspaceId.isEmpty()) {
-        headers.put("X-Databricks-Org-Id", workspaceId);
-      }
-
       return headers;
     } catch (DatabricksException e) {
       String msg = String.format("%s auth: %s", credentialsProvider.authType(), e.getMessage());
@@ -732,23 +727,14 @@ public boolean isAws() {
   }
 
   public boolean isAccountClient() {
-    if (getHostType() == HostType.UNIFIED) {
-      throw new DatabricksException(
-          "Cannot determine account client status for unified hosts. "
-              + "Use getHostType() or getClientType() instead. "
-              + "For unified hosts, client type depends on whether workspaceId is set.");
-    }
     if (host == null) {
       return false;
     }
     return host.startsWith("https://accounts.") || host.startsWith("https://accounts-dod.");
   }
 
-  /** Returns the host type based on configuration settings and host URL. */
+  /** Returns the host type based on the host URL pattern. */
   public HostType getHostType() {
-    if (experimentalIsUnifiedHost != null && experimentalIsUnifiedHost) {
-      return HostType.UNIFIED;
-    }
     if (host == null) {
       return HostType.WORKSPACE;
     }
@@ -758,15 +744,10 @@ public HostType getHostType() {
     return HostType.WORKSPACE;
   }
 
-  /** Returns the client type based on host type and workspace ID configuration. */
+  /** Returns the client type based on host type. */
   public ClientType getClientType() {
     HostType hostType = getHostType();
     switch (hostType) {
-      case UNIFIED:
-        // For unified hosts, client type depends on whether workspaceId is set
-        return (workspaceId != null && !workspaceId.isEmpty())
-            ? ClientType.WORKSPACE
-            : ClientType.ACCOUNT;
       case ACCOUNTS:
         return ClientType.ACCOUNT;
       case WORKSPACE:
@@ -903,24 +884,11 @@ private OpenIDConnectEndpoints fetchOidcEndpointsFromDiscovery() {
     return null;
   }
 
-  private OpenIDConnectEndpoints getUnifiedOidcEndpoints(String accountId) throws IOException {
-    if (accountId == null || accountId.isEmpty()) {
-      throw new DatabricksException(
-          "account_id is required for unified host OIDC endpoint discovery");
-    }
-    String prefix = getHost() + "/oidc/accounts/" + accountId;
-    return new OpenIDConnectEndpoints(prefix + "/v1/token", prefix + "/v1/authorize");
-  }
-
   private OpenIDConnectEndpoints fetchDefaultOidcEndpoints() throws IOException {
     if (getHost() == null) {
       return null;
     }
 
-    // For unified hosts, use account-based OIDC endpoints
-    if (getHostType() == HostType.UNIFIED) {
-      return getUnifiedOidcEndpoints(getAccountId());
-    }
     if (isAccountClient() && getAccountId() != null) {
       String prefix = getHost() + "/oidc/accounts/" + getAccountId();
       return new OpenIDConnectEndpoints(prefix + "/v1/token", prefix + "/v1/authorize");

databricks-sdk-java/src/main/java/com/databricks/sdk/core/DatabricksConfig.java

@@ -9,8 +9,5 @@ public enum HostType {
   WORKSPACE,
 
   /** Traditional accounts host. */
-  ACCOUNTS,
-
-  /** Unified host supporting both workspace and account operations. */
-  UNIFIED
+  ACCOUNTS
 }

databricks-sdk-java/src/main/java/com/databricks/sdk/core/HostType.java

@@ -2,7 +2,6 @@
 
 import static org.junit.jupiter.api.Assertions.*;
 
-import com.databricks.sdk.core.ClientType;
 import com.databricks.sdk.core.DatabricksConfig;
 import com.databricks.sdk.core.HostType;
 import com.databricks.sdk.service.provisioning.Workspace;
@@ -49,28 +48,14 @@ public void testGetWorkspaceClientForUnifiedHost() {
 
     WorkspaceClient workspaceClient = accountClient.getWorkspaceClient(workspace);
 
-    // Should have the same host
+    // Should have the same host (unified hosts reuse the same host)
     assertEquals(unifiedHost, workspaceClient.config().getHost());
 
     // Should have workspace ID set
     assertEquals("123456", workspaceClient.config().getWorkspaceId());
 
-    // Should be workspace client type (on unified host)
-    assertEquals(ClientType.WORKSPACE, workspaceClient.config().getClientType());
-
-    // Host type should still be unified
-    assertEquals(HostType.UNIFIED, workspaceClient.config().getHostType());
-  }
-
-  @Test
-  public void testGetWorkspaceClientForUnifiedHostType() {
-    // Verify unified host type is correctly detected
-    DatabricksConfig config =
-        new DatabricksConfig()
-            .setHost("https://unified.databricks.com")
-            .setExperimentalIsUnifiedHost(true);
-
-    assertEquals(HostType.UNIFIED, config.getHostType());
+    // Host type is WORKSPACE (determined from URL pattern, not unified flag)
+    assertEquals(HostType.WORKSPACE, workspaceClient.config().getHostType());
   }
 
   @Test

databricks-sdk-java/src/test/java/com/databricks/sdk/AccountClientTest.java

@@ -11,9 +11,7 @@ class DatabricksCliCredentialsProviderTest {
   private static final String CLI_PATH = "/usr/local/bin/databricks";
   private static final String HOST = "https://my-workspace.cloud.databricks.com";
   private static final String ACCOUNT_HOST = "https://accounts.cloud.databricks.com";
-  private static final String UNIFIED_HOST = "https://unified.databricks.com";
   private static final String ACCOUNT_ID = "test-account-123";
-  private static final String WORKSPACE_ID = "987654321";
 
   private final DatabricksCliCredentialsProvider provider = new DatabricksCliCredentialsProvider();
 
@@ -39,104 +37,12 @@ void testBuildHostArgs_AccountHost() {
   }
 
   @Test
-  void testBuildHostArgs_UnifiedHost_WithAccountIdAndWorkspaceId() {
-    DatabricksConfig config =
-        new DatabricksConfig()
-            .setHost(UNIFIED_HOST)
-            .setExperimentalIsUnifiedHost(true)
-            .setAccountId(ACCOUNT_ID)
-            .setWorkspaceId(WORKSPACE_ID);
+  void testBuildHostArgs_NonAccountsHostWithAccountId() {
+    // Non-accounts hosts should not pass --account-id even if accountId is set
+    DatabricksConfig config = new DatabricksConfig().setHost(HOST).setAccountId(ACCOUNT_ID);
 
     List<String> cmd = provider.buildHostArgs(CLI_PATH, config);
 
-    assertEquals(
-        Arrays.asList(
-            CLI_PATH,
-            "auth",
-            "token",
-            "--host",
-            UNIFIED_HOST,
-            "--experimental-is-unified-host",
-            "--account-id",
-            ACCOUNT_ID,
-            "--workspace-id",
-            WORKSPACE_ID),
-        cmd);
-  }
-
-  @Test
-  void testBuildHostArgs_UnifiedHost_WithAccountIdOnly() {
-    DatabricksConfig config =
-        new DatabricksConfig()
-            .setHost(UNIFIED_HOST)
-            .setExperimentalIsUnifiedHost(true)
-            .setAccountId(ACCOUNT_ID);
-
-    List<String> cmd = provider.buildHostArgs(CLI_PATH, config);
-
-    assertEquals(
-        Arrays.asList(
-            CLI_PATH,
-            "auth",
-            "token",
-            "--host",
-            UNIFIED_HOST,
-            "--experimental-is-unified-host",
-            "--account-id",
-            ACCOUNT_ID),
-        cmd);
-  }
-
-  @Test
-  void testBuildHostArgs_UnifiedHost_WithWorkspaceIdOnly() {
-    DatabricksConfig config =
-        new DatabricksConfig()
-            .setHost(UNIFIED_HOST)
-            .setExperimentalIsUnifiedHost(true)
-            .setWorkspaceId(WORKSPACE_ID);
-
-    List<String> cmd = provider.buildHostArgs(CLI_PATH, config);
-
-    assertEquals(
-        Arrays.asList(
-            CLI_PATH,
-            "auth",
-            "token",
-            "--host",
-            UNIFIED_HOST,
-            "--experimental-is-unified-host",
-            "--workspace-id",
-            WORKSPACE_ID),
-        cmd);
-  }
-
-  @Test
-  void testBuildHostArgs_UnifiedHost_WithNoAccountIdOrWorkspaceId() {
-    DatabricksConfig config =
-        new DatabricksConfig().setHost(UNIFIED_HOST).setExperimentalIsUnifiedHost(true);
-
-    List<String> cmd = provider.buildHostArgs(CLI_PATH, config);
-
-    assertEquals(
-        Arrays.asList(
-            CLI_PATH, "auth", "token", "--host", UNIFIED_HOST, "--experimental-is-unified-host"),
-        cmd);
-  }
-
-  @Test
-  void testBuildHostArgs_UnifiedHostFalse_WithAccountHost() {
-    // When experimentalIsUnifiedHost is explicitly false, should fall back to account-id logic
-    DatabricksConfig config =
-        new DatabricksConfig()
-            .setHost(ACCOUNT_HOST)
-            .setExperimentalIsUnifiedHost(false)
-            .setAccountId(ACCOUNT_ID);
-
-    List<String> cmd = provider.buildHostArgs(CLI_PATH, config);
-
-    assertEquals(
-        Arrays.asList(
-            CLI_PATH, "auth", "token", "--host", ACCOUNT_HOST, "--account-id", ACCOUNT_ID),
-        cmd);
+    assertEquals(Arrays.asList(CLI_PATH, "auth", "token", "--host", HOST), cmd);
   }
 }