add default value to user-agent parameter

README.md

@@ -12,8 +12,8 @@ Databricks input plugin for Embulk loads records from Databricks.
 - **driver_path**: path to the jar file of the JDBC driver. If not set, [the bundled JDBC driver](https://docs.databricks.com/en/integrations/jdbc/index.html) will be used. (string, optional)
 - **options**: extra JDBC properties (hash, default: {})
 - **user_agent**: set user agent property to JDBC connection. If 'UserAgentEntry' property is specified in the **options**, it will be overwritten by this value. (hash, optional)
-  - **product_name**: product name of user agent (string)
-  - **product_version**: product version of user agent (string)
+  - **product_name**: product name of user agent (string, default: "unknown")
+  - **product_version**: product version of user agent (string, default: "0.0.0")
 - **server_hostname**: The Databricks compute resource’s Server Hostname value, see [Compute settings for the Databricks JDBC Driver](https://docs.databricks.com/en/integrations/jdbc/compute.html). (string, required)
 - **http_path**: The Databricks compute resource’s HTTP Path value, see [Compute settings for the Databricks JDBC Driver](https://docs.databricks.com/en/integrations/jdbc/compute.html). (string, required)
 - **personal_access_token**: The Databaricks personal_access_token, see [Authentication settings for the Databricks JDBC Driver](https://docs.databricks.com/en/integrations/jdbc/authentication.html#authentication-pat). (string, required)

src/main/java/org/embulk/input/DatabricksInputPlugin.java

@@ -3,7 +3,6 @@
 import java.sql.Connection;
 import java.sql.DriverManager;
 import java.sql.SQLException;
-import java.util.Map;
 import java.util.Optional;
 import java.util.Properties;
 import org.embulk.config.ConfigException;
@@ -12,6 +11,7 @@
 import org.embulk.spi.Schema;
 import org.embulk.util.config.Config;
 import org.embulk.util.config.ConfigDefault;
+import org.embulk.util.config.Task;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -42,8 +42,18 @@ public interface DatabricksPluginTask extends PluginTask {
     public Optional<String> getSchemaName();
 
     @Config("user_agent")
-    @ConfigDefault("null")
-    public Optional<Map<String, String>> getUserAgent();
+    @ConfigDefault("{}")
+    public Optional<UserAgentEntry> getUserAgent();
+
+    public interface UserAgentEntry extends Task {
+      @Config("product_name")
+      @ConfigDefault("\"unknown\"")
+      public String getProductName();
+
+      @Config("product_version")
+      @ConfigDefault("\"0.0.0\"")
+      public String getProductVersion();
+    }
   }
 
   @Override
@@ -82,8 +92,8 @@ protected JdbcInputConnection newConnection(PluginTask task) throws SQLException
     props.putAll(t.getOptions());
     // overwrite UserAgentEntry property if the same property is set in options
     if (t.getUserAgent().isPresent()) {
-      String product_name = t.getUserAgent().get().get("product_name");
-      String product_version = t.getUserAgent().get().get("product_version");
+      String product_name = t.getUserAgent().get().getProductName();
+      String product_version = t.getUserAgent().get().getProductVersion();
 
       props.put("UserAgentEntry", product_name + "/" + product_version);
     }