Fix code review issues: duplicate assertion, copyright header, Javadoc example

Agent-Logs-Url: https://github.com/github/copilot-sdk-java/sessions/16d575c4-83f4-4d20-99d9-b48635b3791d

Co-authored-by: edburns <75821+edburns@users.noreply.github.com>

Author: Copilot

src/main/java/com/github/copilot/sdk/json/GetSessionMetadataResponse.java

@@ -1,3 +1,7 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *--------------------------------------------------------------------------------------------*/
+
 package com.github.copilot.sdk.json;
 
 import com.fasterxml.jackson.annotation.JsonInclude;

src/main/java/com/github/copilot/sdk/json/SessionUiApi.java

@@ -18,8 +18,8 @@
  * <h2>Example Usage</h2>
  *
  * <pre>{@code
- * if (Boolean.TRUE
- * 		.equals(session.getCapabilities().getUi() != null && session.getCapabilities().getUi().getElicitation())) {
+ * var caps = session.getCapabilities();
+ * if (caps.getUi() != null && Boolean.TRUE.equals(caps.getUi().getElicitation())) {
  * 	boolean confirmed = session.getUi().confirm("Are you sure?").get();
  * }
  * }</pre>

src/test/java/com/github/copilot/sdk/ElicitationTest.java

@@ -44,7 +44,6 @@ void sessionCapabilitiesTypesAreProperlyStructured() {
         // Test with null UI
         var emptyCapabilities = new SessionCapabilities();
         assertNull(emptyCapabilities.getUi());
-        assertNull(emptyCapabilities.getUi());
     }
 
     @Test