Use new evaluations endpoint by liamhughes · Pull Request #7 · OctopusDeploy/openfeature-provider-java

liamhughes · 2026-03-30T04:37:36Z

Background

The client percentage rollout feature requires ClientRolloutPercentage and EvaluationKey to be included in evaluation responses.

We were unable to add these fields to the existing GET /featuretoggles/v3 evaluations endpoint because the Java OpenFeature provider (in this repo) was previously using Jackson with strict deserialisation (FAIL_ON_UNKNOWN_PROPERTIES = true). Even though we relaxed this in #5, we still can't change the existing endpoint because there are deployed versions of the older serialisation configuration.

This PR updates the provider to use the new endpoint, which has the following changes compared to the old endpoint:

The name field was removed
evaluationKey and clientRolloutPercentage were added, though are only returned if isEnabled evaluated to true in the feature toggles service
segments are also only returned if isEnabled evaluated to true

Changes

Update URI called my provider and in test WireMock server
Updates to FeatureToggleEvaluation class
- Removed name property and getter
- Added evaluationKey and clientRolloutPercentage properties with Optional getters
- Updated getSegments to Optional getter
- Added hasSegments convenience method
Updates to OctopusContext class
- Type changes from FeatureToggleEvaluation
- Added missingRequiredPropertiesForClientSideEvaluation check

Notes for review

While Java does not support nullable reference types (i.e. all reference fields could be null) we can use the Optional<T> type to make it explicit which getter values should be checked or defaulted.
The new fields are not actually being used yet, but will be in the next PR.

Testing

All existing tests are passing, albeit with some change in test data.
The majority of specification tests at this commit pass, except those relying on the client rollout functionality. As such, I have disabled the specification tests because there isn't a commit in OctopusDeploy/openfeature-provider-specification that uses the new endpoint response shape that doesn't also expect the client percentage rollout feature to be implemented. This will be implemented and fully tested in the next PR, prior to the next release of this library

…lloutPercentage

Copilot

Pull request overview

Updates the Java OpenFeature provider to call the newer evaluations endpoint so the provider can consume updated evaluation payloads (including fields needed for client percentage rollout) without breaking older deployed clients.

Changes:

Switched the evaluations URI to /api/toggles/evaluations/v3/ (provider + WireMock test server).
Updated FeatureToggleEvaluation to remove name, and add evaluationKey, clientRolloutPercentage, and Optional-based accessors for nullable fields.
Updated OctopusContext evaluation flow to account for the new nullable fields and fail fast when required fields for client-side evaluation are missing.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/main/java/com/octopus/openfeature/provider/OctopusClient.java	Calls the new evaluations endpoint and updates Jackson `TypeReference` usage.
src/main/java/com/octopus/openfeature/provider/FeatureToggleEvaluation.java	Adjusts evaluation model to match the new endpoint (new fields + `Optional` getters).
src/main/java/com/octopus/openfeature/provider/OctopusContext.java	Adds validation for required client-side evaluation properties; updates segment evaluation to use `Optional` segments.
src/test/java/com/octopus/openfeature/provider/Server.java	Updates WireMock stubbed path to the new evaluations endpoint.
src/test/java/com/octopus/openfeature/provider/OctopusContextTests.java	Updates test data shape and adds ParseError coverage for missing required evaluation fields.
src/test/java/com/octopus/openfeature/provider/FeatureToggleEvaluationDeserializationTests.java	Updates deserialization assertions for the new model shape (`Optional` segments, removed `name`).

Comments suppressed due to low confidence (1)

src/test/java/com/octopus/openfeature/provider/FeatureToggleEvaluationDeserializationTests.java:34

The model now includes evaluationKey and clientRolloutPercentage, but the deserialization tests don't assert their presence/absence for enabled vs disabled toggles. Add assertions (and update fixtures if needed) to ensure these fields are correctly deserialized into the new Optional getters, so regressions in the new endpoint shape are caught.

    @Test
    void shouldDeserializeEnabledToggle() throws Exception {
        FeatureToggleEvaluation result = objectMapper.readValue(resource("toggle-enabled-no-segments.json"), FeatureToggleEvaluation.class);

        assertThat(result.getSlug()).isEqualTo("my-feature");
        assertThat(result.isEnabled()).isTrue();
        assertThat(result.getSegments()).isEmpty();
    }

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Copilot · 2026-03-30T04:48:44Z

src/main/java/com/octopus/openfeature/provider/FeatureToggleEvaluation.java

-    public String getName() {
-        return name;
+        this.evaluationKey = evaluationKey;
+        this.segments = segments;


segments is assigned directly from the constructor parameter and later wrapped with Collections.unmodifiableList(...) in the getter. This still allows external mutation if the original list reference is retained (e.g., callers constructing FeatureToggleEvaluation directly), which can lead to hard-to-trace behavior changes. Consider making a defensive copy in the constructor (e.g., List.copyOf(segments) when non-null) so the instance is truly immutable.

Suggested change

this.segments = segments;

this.segments = segments == null ? null : List.copyOf(segments);

Low risk, but seems good to me.

src/test/java/com/octopus/openfeature/provider/FeatureToggleEvaluationDeserializationTests.java

Copilot

Pull request overview

Copilot reviewed 18 out of 18 changed files in this pull request and generated 4 comments.

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Copilot · 2026-03-30T05:19:10Z

src/main/java/com/octopus/openfeature/provider/OctopusContext.java

+        if (!evaluation.isEnabled()) {
+            return false;
+        }
+
+        return evaluation.getClientRolloutPercentage().isEmpty()
+                || evaluation.getEvaluationKey().isEmpty()
+                || evaluation.getSegments().isEmpty();


missingRequiredPropertiesForClientSideEvaluation causes evaluate(...) to throw ParseError for any enabled toggle where segments is missing, even though evaluate can safely treat missing segments as "no targeting" (and you already have a fixture covering a missing segments field). This changes behavior from returning the server-provided isEnabled value to falling back to the caller’s default. Consider treating a missing segments field as an empty list (or only requiring segments when client-side targeting/rollout evaluation is actually performed).

Suggested change

if (!evaluation.isEnabled()) {

return false;

}

return evaluation.getClientRolloutPercentage().isEmpty()

|| evaluation.getEvaluationKey().isEmpty()

|| evaluation.getSegments().isEmpty();

// Client-side evaluation is only applicable when the toggle is enabled and has segments

if (!evaluation.isEnabled() || !evaluation.hasSegments()) {

return false;

}

return evaluation.getClientRolloutPercentage().isEmpty()

|| evaluation.getEvaluationKey().isEmpty();

I think this might be correct. Will give it more thought tomorrow.

This matches what the .NET client is doing and passes the missing-client-validation-fields specification tests.

Copilot · 2026-03-30T05:19:10Z

src/main/java/com/octopus/openfeature/provider/OctopusContext.java

+        if (missingRequiredPropertiesForClientSideEvaluation(toggleValue)) {
+            throw new ParseError("Feature toggle " + toggleValue.getSlug() + " is missing necessary information for client-side evaluation.");
        }


The ParseError message is generic and doesn’t indicate which required fields are missing. Including the missing property names (e.g., evaluationKey/segments/clientRolloutPercentage) would make diagnosing malformed responses much easier, especially since the exception causes OpenFeature to fall back to the default value.

Copilot · 2026-03-30T05:19:11Z

src/test/java/com/octopus/openfeature/provider/SpecificationTests.java

    @ParameterizedTest(name = "[{0}] {1}")
    @MethodSource("fixtureTestCases")
+    @Disabled("Requires either old endpoint to be used, or client rollout percentage to be implemented")
    void evaluate(String fileName, String description, String responseJson, FixtureCase testCase) {


This test suite is now fully disabled. That removes the only end-to-end coverage against the provider specification fixtures and makes it easier for future changes to regress behavior unnoticed. Consider marking these as a separate tagged/optional suite (e.g., via JUnit @Tag + build profile) or splitting out the cases that still apply so some specification coverage continues to run in CI.

Haven't had these all this time, I guess it's fine to disable them for a bit.

Temporary circumstance as per PR description.

Copilot · 2026-03-30T05:19:11Z

src/test/java/com/octopus/openfeature/provider/FeatureToggleEvaluationDeserializationTests.java

 import java.io.InputStream;
 import java.util.List;
-import java.util.Map;
+import java.util.Optional;


Unused import java.util.Optional is present but not referenced anywhere in this test class. Removing it will keep the file clean and avoid warnings in stricter build setups.

Suggested change

import java.util.Optional;

dylanlerch · 2026-03-30T05:30:59Z

src/main/java/com/octopus/openfeature/provider/OctopusContext.java

        // this exception will be handled by OpenFeature, and the default value will be used
        if (toggleValue == null) {
-           throw new FlagNotFoundError(); 
+            throw new FlagNotFoundError();


Interesting. Java implementation throws rather than returning an error response?

The specification test seems to confirm this for the parse error case.

Of note: these exception types also exist in the .NET SDK: https://github.com/open-feature/dotnet-sdk/tree/main/src/OpenFeature/Error

We may want to align the clients in one direction or the other at some point.

caitlynstocker

Have picked through the code and can't see any problems ✅

I'm not sure exactly how to do it but have you also tested it manually?

caitlynstocker · 2026-04-01T02:52:22Z

src/main/java/com/octopus/openfeature/provider/FeatureToggleEvaluation.java

+
+    public Optional<List<Segment>> getSegments() {
+        return Optional.ofNullable(segments);
+    }


This is my first time seeing this Optional class, but it sounds right 👍

caitlynstocker · 2026-04-01T03:15:23Z

src/main/java/com/octopus/openfeature/provider/OctopusClient.java

                return null;
            }
-            List<FeatureToggleEvaluation> evaluations = OctopusObjectMapper.INSTANCE.readValue(httpResponse.body(), new TypeReference<List<FeatureToggleEvaluation>>(){}); 
+            List<FeatureToggleEvaluation> evaluations = OctopusObjectMapper.INSTANCE.readValue(httpResponse.body(), new TypeReference<>(){});


Have not seen this before but Claude says you're just telling the deserializer to put the response into a list of FeatureToggleEvaluations. Sounds good 👍

Yeah, this is just a bit of syntax clean up. Because the type of the variable List<FeatureToggleEvaluation> is specified (no var in Java 8), it isn't needed to be specified in the TypeReference<>.

caitlynstocker · 2026-04-01T03:30:53Z

src/test/java/com/octopus/openfeature/provider/FeatureToggleEvaluationDeserializationTests.java


-        assertThat(result.getSegments()).hasSize(2);
-        assertSegmentsContain(result.getSegments(),
+        var segments = result.getSegments().orElseThrow();


If we throw an error here, is it possible to include a message about why?

Same question below.

I could add an explicit check and throw my own exception, but I think it should be clear if it were ever to throw at this line? You can basically think of .orElseThrow() as the same as C#'s !, except it throws right away rather than when you try to reference the variable.

liamhughes · 2026-04-01T04:53:03Z

I'm not sure exactly how to do it but have you also tested it manually?

I have tested against my local OctoToggle service:

package com.octopus.openfeature.provider;

import dev.openfeature.sdk.Client;
import dev.openfeature.sdk.OpenFeatureAPI;
import org.junit.jupiter.api.Test;

import java.net.URI;

import static org.assertj.core.api.Assertions.assertThat;

class OpenFeatureIntegrationTest {

    @Test
    void shouldInitialiseOpenFeatureClientWithOctopusProvider() {
        var config = new OctopusConfiguration("eyJh...");
        config.setServerUri(URI.create("http://localhost:7133"));

        var provider = new OctopusProvider(config);

        OpenFeatureAPI api = OpenFeatureAPI.getInstance();
        api.setProviderAndWait(provider);

        Client client = api.getClient();

        assertThat(client).isNotNull();
        assertThat(api.getProviderMetadata().getName()).isEqualTo("octopus");

        assertThat(client.getBooleanValue("alpha-03", false)).isTrue();
    }

}

liamhughes added 7 commits March 30, 2026 13:02

Update URI

fc413e5

Tidy

ddd25c3

Remove name + make segments optional + add evaluationKey and clientRo…

4e4df5c

…lloutPercentage

Add missingRequiredPropertiesForClientSideEvaluation

c641846

Idiomatic use of Optional

4337999

Self review

4a8ad09

Add parse error unit tests

582f3a9

liamhughes requested a review from Copilot March 30, 2026 04:44

Copilot started reviewing on behalf of liamhughes March 30, 2026 04:44 View session

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liamhughes added 4 commits March 30, 2026 15:53

Temporarily disable specification tests

5427a51

Copilot suggestions

3d8f62e

Update tests

36a7806

Little bits

d9a7acb

liamhughes requested a review from Copilot March 30, 2026 05:14

liamhughes marked this pull request as ready for review March 30, 2026 05:15

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dylanlerch reviewed Mar 30, 2026

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liamhughes requested a review from dylanlerch March 31, 2026 03:09

caitlynstocker reviewed Apr 1, 2026

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liamhughes requested a review from caitlynstocker April 1, 2026 04:54

caitlynstocker approved these changes Apr 1, 2026

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liamhughes merged commit 7b4839f into main Apr 1, 2026
9 checks passed

liamhughes deleted the liamhughes/devex-136-use-new-evaluations-endpoint branch April 1, 2026 05:15

	this.segments = segments;
	this.segments = segments == null ? null : List.copyOf(segments);

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