Fix Big Risk 1. sendExpandedToolResult() bypasses the typed wrapper (HIGH)

scripts/codegen/java.ts
- Remove the special-case `anyOf` rule that picked `String` when exactly 2 non-null branches included a string type. Multi-branch `anyOf` now falls through to `Object`, matching the C# reference generator's behavior.

src/generated/java/com/github/copilot/sdk/generated/rpc/SessionToolsHandlePendingToolCallParams.java
- Change the `result` field type from `String` to `Object` (regenerated output reflecting the `anyOf` rule fix in `java.ts`).

src/main/java/com/github/copilot/sdk/CopilotSession.java
- Replace the `sendExpandedToolResult(requestId, toolResult)` call with a direct typed-wrapper call: `getRpc().tools.handlePendingToolCall(new SessionToolsHandlePendingToolCallParams(...))`.
- Delete the `sendExpandedToolResult()` private method and its Javadoc block, which are no longer needed now that the `result` field accepts `Object`.

Signed-off-by: Ed Burns <edburns@microsoft.com>

Author: edburns

scripts/codegen/java.ts

@@ -113,15 +113,9 @@ function schemaTypeToJava(
             const result = schemaTypeToJava(nonNull[0] as JSONSchema7, required && !hasNull, context, propName, nestedTypes);
             return result;
         }
-        // When exactly two non-null types and one of them is string, prefer String
-        // over Object to avoid unnecessary type erasure on common wire-level unions
-        // (e.g., string | null, string | boolean).  For wider unions keep Object.
-        if (nonNull.length === 2) {
-            const hasString = nonNull.some((s) => typeof s === "object" && (s as JSONSchema7).type === "string");
-            if (hasString) {
-                return { javaType: "String", imports };
-            }
-        }
+        // Multi-branch anyOf: fall through to Object, matching the C# generator's
+        // behavior.  Java has no union types, so Object is the correct erasure for
+        // anyOf[string, object] and similar multi-variant schemas.
         console.warn(`[codegen] ${context}.${propName}: anyOf with ${nonNull.length} non-null branches — falling back to Object`);
         return { javaType: "Object", imports };
     }

src/generated/java/com/github/copilot/sdk/generated/rpc/SessionToolsHandlePendingToolCallParams.java

@@ -822,7 +822,8 @@ private void executeToolAndRespondAsync(String requestId, String toolName, Strin
                             toolResult = ToolResultObject
                                     .success(result instanceof String s ? s : MAPPER.writeValueAsString(result));
                         }
-                        sendExpandedToolResult(requestId, toolResult);
+                        getRpc().tools.handlePendingToolCall(
+                                new SessionToolsHandlePendingToolCallParams(sessionId, requestId, toolResult, null));
                     } catch (Exception e) {
                         LOG.log(Level.WARNING, "Error sending tool result for requestId=" + requestId, e);
                     }
@@ -857,25 +858,6 @@ private void executeToolAndRespondAsync(String requestId, String toolName, Strin
         }
     }
 
-    /**
-     * Sends a {@code ToolResultObject} back via
-     * {@code session.tools.handlePendingToolCall} using an
-     * {@link com.fasterxml.jackson.databind.node.ObjectNode} payload.
-     * <p>
-     * {@link SessionToolsHandlePendingToolCallParams#result()} is typed as
-     * {@code String} by the code generator's {@code anyOf[string,object]}
-     * preference rule, but the protocol requires a JSON object for expanded
-     * {@code ToolResultObject} results. This helper bypasses the type constraint
-     * while keeping every other call site on the typed wrapper.
-     */
-    private void sendExpandedToolResult(String requestId, ToolResultObject toolResult) {
-        var node = MAPPER.createObjectNode();
-        node.put("sessionId", sessionId);
-        node.put("requestId", requestId);
-        node.set("result", MAPPER.valueToTree(toolResult));
-        rpc.invoke("session.tools.handlePendingToolCall", node, Object.class);
-    }
-
     /**
      * Builds a {@link SessionUiHandlePendingElicitationParams} carrying a
      * {@code cancel} action, used when an elicitation handler throws or the handler