fix: serialize booleans as native JSON in precomputed request body

[leoromanovsky]

Motivation

The buildRequestBody() method in EppoPrecomputedClient was converting all non-numeric attribute values to strings, including booleans. This caused boolean attributes to be sent in the wrong wire format:

Before (incorrect):

{
  "categoricalAttributes": {
    "isPremium": "true",
    "hasPushEnabled": "false"
  }
}

After (correct):

{
  "categoricalAttributes": {
    "isPremium": true,
    "hasPushEnabled": false
  }
}

This fix aligns the Android SDK with the JS SDK and iOS SDK (see ios-sdk#95), which preserve native boolean types in the wire format.

The shared test data in sdk-test-data/configuration-wire/precomputed-v1.json confirms that booleans should be native JSON booleans:

"categoricalAttributes": {
  "hasPushEnabled": false,
  "buildNumber": 42
}

Changes

• Add ContextAttributesSerializer utility class for consistent attribute serialization
• Properly handle booleans as native JSON booleans in categorical attributes
• Exclude null values from serialization (matching JS/iOS behavior)
• Simplify buildRequestBody() by using the new utility
• Add comprehensive unit tests for wire format verification
• Add precomputed-v1.json test data for integration tests

Decisions

• Created a dedicated utility class (ContextAttributesSerializer) for testability and reuse across subject attributes and bandit actions
• Used Map<String, Object> for categorical attributes instead of Map<String, String> to allow native boolean values

Test plan

• Run unit tests: ./gradlew :eppo:testDebugUnitTest
• Run instrumented tests: ./gradlew :eppo:connectedDebugAndroidTest
• Verify wire format matches expected output in real API calls

[Copilot]

Pull request overview

This PR fixes a bug where boolean attributes were incorrectly serialized as strings ("true", "false") instead of native JSON booleans (true, false) in the precomputed request body. This aligns the Android SDK's wire format with the JS and iOS SDKs.

Changes:

• Introduced ContextAttributesSerializer utility for consistent attribute serialization across subject and bandit action attributes
• Updated serialization to preserve booleans as native JSON types and exclude null values
• Version bumped to 4.12.1

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
eppo/src/main/java/cloud/eppo/android/util/ContextAttributesSerializer.java	New utility class that properly handles boolean serialization as native JSON types
eppo/src/main/java/cloud/eppo/android/EppoPrecomputedClient.java	Refactored to use the new serializer utility, removing duplicated serialization logic
eppo/src/test/java/cloud/eppo/android/ContextAttributesSerializerTest.java	Comprehensive unit tests verifying wire format correctness
eppo/build.gradle	Version bump to 4.12.1

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[aarsilv]

Good catch and glad we have a shared test case now that exercises this.

Approving with two minor comments you can take or leave:

• The new EppoValue.unwrap() method may be useful
• Consideration of null-valued attributes

[aarsilv]

Should we be adding null as the value if it is null?

[leoromanovsky]

We explicitly skip null in swift and javascript so I was matching that behavior.

[aarsilv]

I wonder if the newly-added unrwap() could help simplify things here.

https://github.com/Eppo-exp/sdk-common-jdk/blob/main/src/main/java/cloud/eppo/api/EppoValue.java#L110

[leoromanovsky]

Thanks, good suggestion, hadn't explore the common java repo.

[leoromanovsky]

It doesn't simplify the code for us because we need to know the variation type, would look like this:

  // We'd still need the same if/else chain to pick the VariationType
  if (value.isNumeric()) {
      numericAttrs.put(key, value.unwrap(VariationType.NUMERIC));   // Double
  } else if (value.isBoolean()) {
      categoricalAttrs.put(key, value.unwrap(VariationType.BOOLEAN)); // Boolean
  } else {
      categoricalAttrs.put(key, value.unwrap(VariationType.STRING));  // String
  }

Is that what you were trying to simplify?

[leoromanovsky]

It would be more helpful to augment the EppoValue in jdk common to auto detect the type:

public Object unwrap() {
  switch (this.type) {
    case BOOLEAN: return boolValue;
    case NUMBER: return doubleValue;
    case STRING: return stringValue;
    ...
  }
}

Then the serializer becomes:

if (value.isNumeric()) {
  numericAttrs.put(key, (Number) value.unwrap());
} else {
  categoricalAttrs.put(key, value.unwrap());
}

[aarsilv]

💪

[aarsilv]

I like that we pulled this out into it's own testable class. Since we're doing that, let's include a test for null valued attributes to cover that base.