fix: NullPointerException on first feature flag retrieval

.github/workflows/pr.yaml

@@ -9,11 +9,11 @@ jobs:
         uses: actions/checkout@v4
       - name: Validate Gradle Wrapper
         uses: gradle/wrapper-validation-action@v3
-      - name: Setup Java
+      - name: Set up JDK 21
         uses: actions/setup-java@v4
         with:
-          distribution: temurin
-          java-version: 21
+          distribution: 'graalvm'
+          java-version: '21'
       - name: Setup Gradle
         uses: gradle/gradle-build-action@v2
       - name: Build

.github/workflows/release.yaml

@@ -16,10 +16,10 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - name: Set up JDK 21
-        uses: actions/setup-java@v2
+        uses: actions/setup-java@v4
         with:
+          distribution: 'graalvm'
           java-version: '21'
-          distribution: 'temurin'
       - name: Setup Gradle
         uses: gradle/gradle-build-action@v2
       - name: Publish to Sonatype

build.gradle.kts

@@ -30,6 +30,7 @@ java {
 
     toolchain {
         languageVersion = JavaLanguageVersion.of(21)
+        vendor.set(JvmVendorSpec.GRAAL_VM)
         nativeImageCapable = true
     }
 }

settings.gradle.kts

@@ -1,2 +1,5 @@
 rootProject.name = "posthog-java"
 
+plugins {
+    id("org.gradle.toolchains.foojay-resolver-convention") version "0.8.0"
+}

src/main/java/net/hollowcube/posthog/PostHogClientImpl.java

@@ -86,17 +86,18 @@ public final class PostHogClientImpl implements PostHogClient {
         this.setPropertyIfAbsent(this.defaultEventProperties, LIB_VERSION, DEFAULT_LIBRARY_VERSION);
         this.eventBatchTimeout = eventBatchTimeout;
 
+        this.allowRemoteFeatureFlagEvaluation = allowRemoteFeatureFlagEvaluation;
+        this.sendFeatureFlagEvents = sendFeatureFlagEvents;
+        this.featureFlagsRequestTimeout = featureFlagsRequestTimeout;
+
+        this.exceptionMiddleware = exceptionMiddleware;
+
         // Always enable local evaluation with personal api key.
         if (this.personalApiKey != null) {
             this.featureFlagFetchTimer = new Timer(this::loadRemoteFeatureFlags, featureFlagsPollingInterval);
         } else if (!allowRemoteFeatureFlagEvaluation) {
             throw new IllegalArgumentException("Personal API key is required when remote feature flag evaluation is disabled");
         } else this.featureFlagFetchTimer = null;
-        this.allowRemoteFeatureFlagEvaluation = allowRemoteFeatureFlagEvaluation;
-        this.sendFeatureFlagEvents = sendFeatureFlagEvents;
-        this.featureFlagsRequestTimeout = featureFlagsRequestTimeout;
-
-        this.exceptionMiddleware = exceptionMiddleware;
     }
 
     @Override