[BUG] `LiveRequest.fromJsonString` cannot deserialize any LiveRequest (`@JsonCreator` declared outside `Builder`)

[SuperCorleone]

Describe the Bug

LiveRequest is annotated @JsonDeserialize(builder = LiveRequest.Builder.class), so Jackson must instantiate the AutoValue Builder via a @JsonCreator factory. That factory (jacksonBuilder()) is declared in the enclosing LiveRequest class instead of inside the Builder class, so Jackson finds no creator and throws. As a result LiveRequest.fromJsonString(...) (a public API) fails for every input — even the JSON produced by LiveRequest.toJson(). Serialization works; the object can be written but never read back.

Root Cause

@AutoValue.Builder
@JsonPOJOBuilder(buildMethodName = "build", withPrefix = "")
public abstract static class Builder {
    ...
    public final LiveRequest build() { ... }
}                                   // <-- Builder ends here

public static Builder builder() { return new AutoValue_LiveRequest.Builder().close(false); }
public abstract Builder toBuilder();
public static LiveRequest fromJsonString(String json) {
    return JsonBaseModel.fromJsonString(json, LiveRequest.class);
}
@JsonCreator                        // <-- BUG: outside Builder; Jackson can't find a creator for Builder
static LiveRequest.Builder jacksonBuilder() {
    return LiveRequest.builder();
}

Every other model in the codebase places @JsonCreator jacksonBuilder() inside its Builder class (e.g. LlmResponse.java:114-119, StdioServerParameters, MemoryEntry, EventCompaction); LiveRequest is the lone outlier. (Note: the dev websocket handler reconstructs LiveRequest manually from a parsed JsonNode rather than calling fromJsonString, consistent with this API being unusable.)

Steps to Reproduce

LiveRequest req = LiveRequest.builder()
    .content(Content.builder().parts(Part.fromText("hi")).build())
    .close(false).build();
String json = req.toJson();                              // OK
LiveRequest back = JsonBaseModel.fromJsonString(json, LiveRequest.class);  // throws

Even minimal {"close":true} fails.

Expected Behavior

fromJsonString deserializes any valid LiveRequest JSON, including the output of toJson() (round-trip).

Observed Behavior

IllegalStateException (wrapping)
  Caused by: com.fasterxml.jackson.databind.exc.InvalidDefinitionException:
  Cannot construct instance of `com.google.adk.agents.LiveRequest$Builder`
  (no Creators, like default constructor, exist): cannot deserialize from Object value

Suggested Fix

Move jacksonBuilder() inside the Builder class, matching the rest of the codebase:

public abstract static class Builder {
    ...
    @JsonCreator
    static LiveRequest.Builder jacksonBuilder() { return LiveRequest.builder(); }
    public final LiveRequest build() { ... }
}

Corresponding Test (generated)

@Test
public void testLiveRequestToJsonRoundTrip() {
    // Given
    Content content = Content.builder()
        .parts(Part.fromText("Test content"))
        .build();
    
    LiveRequest liveRequest = LiveRequest.builder()
        .content(content)
        .close(false)
        .build();

    // When
    String json = liveRequest.toJson();
    // Since LiveRequest has a complex builder pattern and Jackson struggles with it,
    // we'll test the serialization/deserialization using JsonBaseModel directly
    // but verify that the JSON can be parsed back into the same object type
    LiveRequest deserialized = JsonBaseModel.fromJsonString(json, LiveRequest.class);

    // Then
    assertNotNull(json);
    assertNotNull(deserialized);
    assertTrue(deserialized.content().isPresent());
    assertEquals(content, deserialized.content().get());
    assertFalse(deserialized.shouldClose());
}

Environment

• Project: adk / google-adk (com.google.adk) · upstream: github.com/google/adk-java
• Version: 0.5.1-SNAPSHOT (local) · Commit: <fill SUT commit>
• Java 17 · OS macOS

This input was generated by the test case generator TestFusion developed in our STAR lab.

[hemasekhar-p]

Hi @SuperCorleone, Thank you for reporting this issue. I am able to reproduce this issue in latest version which you described and I have created this PR to resolve this problem. hope this will resolve your issue?