feat: LDContext is java.io.Serializable

[joshfriend]

Requirements

• I have added test coverage for new or changed functionality
• I have followed the repository's pull request submission guidelines
• I have validated my changes against all supported platform versions

Describe the solution you've provided

I Added Serializable to any base classes and interfaces needed to make LDContext itself serializable

Describe alternatives you've considered

My workaround for this was to manually serialize the LDContext to json because string is serializable and deserialize it again

Additional context

I was trying to use launchdarkly sdks inside of some gradle tooling that configures build features based on feature flags. To do this I wrote a ValueSource which took the following parameters:

• Feature flag key
• SDK key
• LDContext

And gradle threw an error because LDContext is not serializable, and therefore not allowed as a ValueSourceParameters property.

I'm hoping that code will be open source soon, but for now here's a snippet:

abstract class LDBooleanValueSource: ValueSource<Boolean, LDBooleanValueSource.Params> {
  interface Params : ValueSourceParameters {
    val flagName: Property<String>
    val sdkKey: Property<String>
    val context: Property<LDContext> // Not serializable!
  }

  companion object {
    private val config: LDConfig = LDConfig.Builder().build()

    @JvmStatic
    fun ProviderFactory.launchDarklyBoolean(flagName: String, context: LDContext): Provider<Boolean> {
      return of(LDBooleanValueSource::class.java) {
        it.parameters.flagName.set(flagName)
        it.parameters.sdkKey.set(gradleProperty("launchdarkly.sdkKey"))
        it.parameters.context.set(context)
      }
    }
  }

  private val client by lazy { LDClient(parameters.sdkKey.get(), config) }

  override fun obtain(): Boolean =
    client.allFlagsState(parameters.context.get())
      .getFlagValue(parameters.flagName.get())
      .booleanValue()
}

---

Note

Low Risk
Additive API change on marker interfaces and internal types; behavior is covered by new serialization round-trip tests with no runtime path changes for normal SDK usage.

Overview
Enables Java native serialization (ObjectOutputStream / ObjectInputStream) for LDContext, so it can be used in frameworks that require Serializable parameters (e.g. Gradle ValueSource configuration) without JSON workarounds.

JsonSerializable now extends java.io.Serializable, which propagates serializability to LDContext and related JSON-modeled SDK types. AttributeMap is also marked Serializable directly. LDValueBool and LDValueNull add readResolve() so deserialized values restore the canonical singleton instances—required for equals() to behave correctly after a round trip.

New tests in LDContextTest assert single- and multi-kind contexts survive a Java serialize/deserialize cycle and remain equalTo the original.

^{Reviewed by Cursor Bugbot for commit f1ed0c7. Bugbot is set up for automated code reviews on this repo. Configure here.}

[tanderson-ld]

Hi @joshfriend and thank you for the contribution. I will try to take a look in the next day or two.

[tanderson-ld]

Thanks for your patience this week.

[tanderson-ld]

It seems a little unusual to me to make a builder serializable. Do you know which structure is leading the default serialization here? I don't see the dependency from LDContext to here.

[tanderson-ld]

Is it the ArrayBuilder in LDValue?

[joshfriend]

I backed this one out, it doesn't need to be serializable.

[joshfriend]

I rebased this and added a roundtrip serialization test