[spring-ai] NullPointerException in ToolConverter when ADK tool uses ToolContext

[lurongjiang]

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Describe the bug
In com.google.adk.models.springai.ToolConverter#convertToSpringAiTools, when converting ADK BaseTool instances to Spring AI ToolCallback, the toolContext parameter passed to tool.runAsync(...) is hardcoded as null. This causes a NullPointerException if the underlying ADK tool method expects and uses a non-null ToolContext (e.g., to access functionCallId()).

To Reproduce
Steps to reproduce the behavior:

1. Define an ADK tool method that includes a ToolContext parameter.
2. Use ToolConverter to convert this tool into a Spring AI ToolCallback.
3. Invoke the resulting ToolCallback.call(...) with a valid org.springframework.ai.chat.model.ToolContext.
4. Observe a NullPointerException because the ADK tool receives null for its ToolContext argument.

test case:

@Test
void testCallbackWithToolContext() throws Exception {
  ToolConverter converter = new ToolConverter();
  FunctionTool tool = FunctionTool.create(TestSayHelloFunctions.class, "sayHello");
  Map<String, BaseTool> tools = Map.of("sayHello", tool);

  List<ToolCallback> toolCallbacks = converter.convertToSpringAiTools(tools);
  ToolCallback callback = toolCallbacks.get(0);
  String res = callback.call("{\"name\":\"Jack\"}", new org.springframework.ai.chat.model.ToolContext(new HashMap<>()));
  System.out.println(res);
}

public static class TestSayHelloFunctions {
  @Annotations.Schema(name = "sayHello", description = "Test func: say hello for name")
  public static void sayHello(
      @Annotations.Schema(name = "name", description = "the name to say hello") String name,
      @Annotations.Schema(name = "toolContext", description = "toolContext") ToolContext toolContext) {
    toolContext.functionCallId().ifPresent(functionCallId -> System.out.println("callId:" + functionCallId));
    System.out.println("hello " + name);
  }
}

Expected behavior
The ADK ToolContext passed to the tool method should be constructed from the org.springframework.ai.chat.model.ToolContext provided to ToolCallback.call(...), rather than being null. At minimum, it should not cause an NPE when the tool expects a non-null context.

Screenshots
If applicable, add screenshots to help explain your problem.

Desktop (please complete the following information):

• OS: windows 11
• Java version: jdk17
• ADK version(see maven dependency):

  <groupId>com.google.adk</groupId>
  <artifactId>google-adk-parent</artifactId>
  <version>0.5.1-SNAPSHOT</version>

Additional context

18:33:59.235 [main] ERROR com.google.adk.tools.FunctionTool -- Exception occurred while calling function tool: sayHello
java.lang.reflect.InvocationTargetException: null
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:568)
	at com.google.adk.tools.FunctionTool.call(FunctionTool.java:238)
	at com.google.adk.tools.FunctionTool.runAsync(FunctionTool.java:227)
	at com.google.adk.models.springai.ToolConverter.lambda$convertToSpringAiTools$3(ToolConverter.java:144)
	at org.springframework.ai.tool.function.FunctionToolCallback.lambda$builder$0(FunctionToolCallback.java:141)
	at org.springframework.ai.tool.function.FunctionToolCallback.callMethod(FunctionToolCallback.java:113)
	at org.springframework.ai.tool.function.FunctionToolCallback.call(FunctionToolCallback.java:104)
	at com.google.adk.models.springai.ToolConverterArgumentProcessingTest.testCallback(ToolConverterArgumentProcessingTest.java:74)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:568)
	...
	at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:35)
	at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:231)
	at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:55)
Caused by: java.lang.NullPointerException: Cannot invoke "com.google.adk.tools.ToolContext.functionCallId()" because "toolContext" is null
	at com.google.adk.models.springai.ToolConverterArgumentProcessingTest$TestSayHelloFunctions.sayHello(ToolConverterArgumentProcessingTest.java:83)
	... 81 common frames omitted
{"status":"error","message":"An internal error occurred."}

[Tharanishwaran]

Hi! I'd like to work on this issue I contribute to CNCF and Spring projects and can fix the NullPointerException by properly mapping Spring AI's ToolContext to ADK's ToolContext in the ToolConverter.