@Client doesn't support java.util.Map return types

[benalexau]

I have put the following JSON file in this GitHub Gist:

{
  "USD": [
    {
      "symbol": "USD.SGD",
      "ccyPair": "SGD"
    },
    {
      "symbol": "USD.RON",
      "ccyPair": "RON"
    }
  ]
}

Java types as follows were attempted to map this:

@Json
public record TestRecord(String symbol, String ccyPair) {}

@Client
public interface TestClient {

  @Get(
      "benalexau/5b6944b31c8a937dc4fc0268a069bb64/raw/2de03fbff0bf2fd171cc3796d40bc7bca63ceb1d/currency-mapping-example.json")
  Map<String, List<TestRecord>> get();
}

With a test method:

  @Test
  void fails() {
    final HttpClient httpClient =
        HttpClient.builder().baseUrl("https://gist.githubusercontent.com").build();

    TestClient client = httpClient.create(TestClient.class);
    Map<String, List<TestRecord>> result = client.get();
    System.out.println(result);
  }

This yields:

No JsonAdapter for java.util.Map<java.util.List, testing.TestRecord>
Possible Causes: 
1. Missing @Json or @Json.Import annotation.
2. The avaje-jsonb-generator dependency was not available during compilation

The generated TestClientImpl has an erroneous type mapping:

  @Override
  public Map<String,List<TestRecord>> get() {
    return client.request()
      .path("benalexau/5b6944b31c8a937dc4fc0268a069bb64/raw/2de03fbff0bf2fd171cc3796d40bc7bca63ceb1d/currency-mapping-example.json")
      .GET()
      .bean(Types.newParameterizedType(Map.class, List.class, TestRecord.class));
  }

This can be worked around by detecting the invalid type and replacing it:

  @Test
  void success() {
    BodyAdapter fakeAdapter =
        new BodyAdapter() {
          private JsonbBodyAdapter delegate = new JsonbBodyAdapter();

          @Override
          public <T> BodyWriter<T> beanWriter(Class<?> type) {
            return delegate.beanWriter(type);
          }

          @Override
          public <T> BodyReader<T> beanReader(Class<T> type) {
            return delegate.beanReader(type);
          }

          @Override
          public <T> BodyReader<T> beanReader(Type type) {
            if (type.toString().contains("java.util.List, testing.TestRecord")) {
              ParameterizedType adjusted = Types.mapOf(Types.listOf(TestRecord.class));
              return delegate.beanReader(adjusted);
            }
            return delegate.beanReader(type);
          }

          @Override
          public <T> BodyReader<List<T>> listReader(Class<T> type) {
            return delegate.listReader(type);
          }
        };
    final HttpClient httpClient =
        HttpClient.builder()
            .baseUrl("https://gist.githubusercontent.com")
            .bodyAdapter(fakeAdapter)
            .build();

    TestClient client = httpClient.create(TestClient.class);
    Map<String, List<TestRecord>> result = client.get();
    System.out.println(result);
  }

Which gives the expected result:

{USD=[TestRecord[symbol=USD.SGD, ccyPair=SGD], TestRecord[symbol=USD.RON, ccyPair=RON]]}

It would be preferable if the generator would support Map.

I will attach the 3 test files to make it easier to reproduce.

MappingTest.java

TestClient.java

TestRecord.java

[SentryMan]

That's a clever workaround, I haven't thought about using BodyAdapter in that way.

[rbygrave]

Fix deployed into version 3.5-RC2 which will be in central in 15 mins or so for you to try / confirm the fix etc.

[benalexau]

I confirm it is fixed in 3.5-RC2. Thanks for such a quick fix, and even a release including it!