## Change
Migrates three more integrations off Retrofit/OkHttp and onto
LangChain4j's own `HttpClient` abstraction
(`dev.langchain4j.http.client`), consistent with the already-migrated
modules (OpenAI, Anthropic,
Mistral, Gemini, Voyage). Each module drops `retrofit`, `okhttp`, and
`converter-jackson`, routes HTTP through the pluggable backend (default
JDK client at runtime), and replaces its hand-rolled logging
interceptors with the abstraction's `LoggingHttpClient`.
**`langchain4j-cohere`**
- `CohereClient` rewritten on `HttpClient`; added `CohereJsonUtils`
mirroring the exact ObjectMapper config (`SNAKE_CASE` + `NON_NULL` +
lenient — DTOs have no `@JsonProperty`, so the wire format is
preserved). Endpoints unchanged: `POST embed` (v1 + v2), `POST rerank`;
`Authorization: Bearer` preserved.
- Deleted `CohereApi` + both interceptors. Added
`httpClientBuilder(...)` to `CohereClient`, `CohereEmbeddingModel`, and
`CohereScoringModel`.
- `proxy(...)` (public on `CohereScoringModel` + a deprecated
constructor) can't be expressed through the abstraction, so it now
**throws `UnsupportedOperationException`** pointing users to
`httpClientBuilder(...)` rather than silently ignoring the proxy. The
builder method is `@Deprecated`.
**`langchain4j-hugging-face`**
- `DefaultHuggingFaceClient` rewritten on `HttpClient`; added
`HuggingFaceJsonUtils` (plain mapper — DTOs self-annotate with
`@JsonNaming`). The `Authorization: Bearer` header from
`ApiKeyInsertingInterceptor`
is replicated on each request. Endpoints unchanged.
- Deleted `HuggingFaceApi` + `ApiKeyInsertingInterceptor`. The
`HuggingFaceClient` interface and the `HuggingFaceClientFactory` SPI
method are unchanged; `HuggingFaceClientFactory.Input` gains a
**`default
HttpClientBuilder httpClientBuilder()`** (backward-compatible — existing
SPI implementors, e.g. quarkus-langchain4j, inherit the `null` default
and are unaffected). Added `httpClientBuilder(...)` to the
chat/language/embedding model builders.
**`langchain4j-workers-ai`**
- `WorkersAiClient` rewritten on `HttpClient`; added
`WorkersAiJsonUtils`. Endpoints/paths/`Authorization` preserved. Image
generation returns raw bytes via `SuccessfulHttpResponse.bodyBytes()`
(no String
round-trip). Cloudflare's `HTTP 200` + `{"success":false}` error
envelope is still surfaced (via a restored `checkSuccess()`), alongside
the automatic `HttpException` for non-2xx.
- Deleted `WorkersAiApi`; added `httpClientBuilder(...)` to all four
model builders. Some internal `.client` plumbing was removed
(`WorkersAiClient` no-arg constructor / `createService` /
`AuthInterceptor`,
and `AbstractWorkersAIModel.processErrors`/`workerAiClient`) —
documented in `revapi.json`.
Each module got a `revapi.json` entry for the intentional
`HttpClientBuilder` exposure (and removals), matching the existing
convention in `langchain4j-chroma`, `langchain4j-open-ai`,
`langchain4j-voyage-ai`,
etc.
**Behavioral note:** on non-2xx responses the clients now throw
`dev.langchain4j.exception.HttpException` (a `RuntimeException`
subclass) instead of a plain `RuntimeException` with a `"status code:
…"` message
— the same behavior all other migrated modules already exhibit.
## General checklist
- [X] There are no breaking changes (API, behaviour)
- [ ] I have added unit and/or integration tests for my change
- [ ] The tests cover both positive and negative cases
- [X] I have manually run all the unit and integration tests in the
module I have added/changed, and they are all green
- [ ] I have manually run all the unit and integration tests in the
[core](https://github.com/langchain4j/langchain4j/tree/main/langchain4j-core)
and
[main](https://github.com/langchain4j/langchain4j/tree/main/langchain4j)
modules, and they are all green
- [ ] I have added/updated the
[documentation](https://github.com/langchain4j/langchain4j/tree/main/docs/docs)
- [ ] I have added an example in the [examples
repo](https://github.com/langchain4j/langchain4j-examples) (only for
"big" features)
- [ ] I have added/updated [Spring Boot
starter(s)](https://github.com/langchain4j/langchain4j-spring) (if
applicable)
Dmytro Liubarskyi