fix: serialize booleans as native JSON in precomputed request body (#243)

* fix: serialize booleans as native JSON in precomputed request body

The buildRequestBody() method was converting all non-numeric attribute
values to strings, including booleans. This caused boolean attributes
like "isPremium: true" to be sent as "isPremium: \"true\"" (string)
instead of "isPremium: true" (native JSON boolean).

This fix aligns the Android SDK with the JS and iOS SDKs, which preserve
native boolean types in the wire format.

Changes:
- Add ContextAttributesSerializer utility for consistent serialization
- Properly handle booleans as native JSON booleans in categorical attrs
- Exclude null values from serialization (matching JS/iOS behavior)
- Add comprehensive unit tests for wire format verification
- Add precomputed-v1.json test data for integration tests

* chore: remove test data file, use make test-data instead

The precomputed-v1.json file should be fetched via `make test-data`
rather than committed to the repository.

* chore: bump version to 4.12.1

* Update eppo/src/test/java/cloud/eppo/android/ContextAttributesSerializerTest.java

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* test: add explicit null-valued attribute tests

Cover both EppoValue.nullValue() and Java null in the attributes map
to document that both are excluded from serialization output.

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: leoromanovsky

eppo/build.gradle

@@ -7,7 +7,7 @@ plugins {
 }
 
 group = "cloud.eppo"
-version = "4.12.0"
+version = "4.12.1"
 
 android {
     buildFeatures.buildConfig true

eppo/src/main/java/cloud/eppo/android/EppoPrecomputedClient.java

@@ -16,6 +16,7 @@
 import cloud.eppo.android.exceptions.MissingApplicationException;
 import cloud.eppo.android.exceptions.MissingSubjectKeyException;
 import cloud.eppo.android.exceptions.NotInitializedException;
+import cloud.eppo.android.util.ContextAttributesSerializer;
 import cloud.eppo.android.util.ObfuscationUtils;
 import cloud.eppo.android.util.Utils;
 import cloud.eppo.api.Attributes;
@@ -645,27 +646,7 @@ private String buildRequestUrl() {
   private String buildRequestBody() throws Exception {
     Map<String, Object> body = new HashMap<>();
     body.put("subject_key", subjectKey);
-
-    Map<String, Object> subjectAttrsMap = new HashMap<>();
-    Map<String, Number> numericAttrs = new HashMap<>();
-    Map<String, String> categoricalAttrs = new HashMap<>();
-
-    if (subjectAttributes != null) {
-      for (String key : subjectAttributes.keySet()) {
-        EppoValue value = subjectAttributes.get(key);
-        if (value != null) {
-          if (value.isNumeric()) {
-            numericAttrs.put(key, value.doubleValue());
-          } else {
-            categoricalAttrs.put(key, value.stringValue());
-          }
-        }
-      }
-    }
-
-    subjectAttrsMap.put("numericAttributes", numericAttrs);
-    subjectAttrsMap.put("categoricalAttributes", categoricalAttrs);
-    body.put("subject_attributes", subjectAttrsMap);
+    body.put("subject_attributes", ContextAttributesSerializer.serialize(subjectAttributes));
 
     if (banditActions != null && !banditActions.isEmpty()) {
       // Transform banditActions to match the expected wire format with numericAttributes and
@@ -674,27 +655,8 @@ private String buildRequestBody() throws Exception {
       for (Map.Entry<String, Map<String, Attributes>> flagEntry : banditActions.entrySet()) {
         Map<String, Map<String, Object>> actionsForFlag = new HashMap<>();
         for (Map.Entry<String, Attributes> actionEntry : flagEntry.getValue().entrySet()) {
-          Map<String, Object> actionAttrsMap = new HashMap<>();
-          Map<String, Number> actionNumericAttrs = new HashMap<>();
-          Map<String, String> actionCategoricalAttrs = new HashMap<>();
-
-          Attributes attrs = actionEntry.getValue();
-          if (attrs != null) {
-            for (String key : attrs.keySet()) {
-              EppoValue value = attrs.get(key);
-              if (value != null) {
-                if (value.isNumeric()) {
-                  actionNumericAttrs.put(key, value.doubleValue());
-                } else {
-                  actionCategoricalAttrs.put(key, value.stringValue());
-                }
-              }
-            }
-          }
-
-          actionAttrsMap.put("numericAttributes", actionNumericAttrs);
-          actionAttrsMap.put("categoricalAttributes", actionCategoricalAttrs);
-          actionsForFlag.put(actionEntry.getKey(), actionAttrsMap);
+          actionsForFlag.put(
+              actionEntry.getKey(), ContextAttributesSerializer.serialize(actionEntry.getValue()));
         }
         serializedBanditActions.put(flagEntry.getKey(), actionsForFlag);
       }

eppo/src/main/java/cloud/eppo/android/util/ContextAttributesSerializer.java

@@ -0,0 +1,59 @@
+package cloud.eppo.android.util;
+
+import cloud.eppo.api.Attributes;
+import cloud.eppo.api.EppoValue;
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * Utility class for serializing subject and action attributes to the wire format expected by the
+ * precomputed flags API.
+ *
+ * <p>The API expects attributes to be separated into:
+ *
+ * <ul>
+ *   <li>numericAttributes: numbers (integers and doubles)
+ *   <li>categoricalAttributes: strings, booleans, and other non-numeric types
+ * </ul>
+ *
+ * <p>This matches the behavior of the JS SDK and ensures consistent wire format across all Eppo
+ * SDKs.
+ */
+public final class ContextAttributesSerializer {
+
+  private ContextAttributesSerializer() {
+    // Prevent instantiation
+  }
+
+  /**
+   * Serializes attributes into the context attributes format expected by the API.
+   *
+   * @param attributes The attributes to serialize (can be null)
+   * @return A map containing "numericAttributes" and "categoricalAttributes" keys
+   */
+  public static Map<String, Object> serialize(Attributes attributes) {
+    Map<String, Object> result = new HashMap<>();
+    Map<String, Number> numericAttrs = new HashMap<>();
+    Map<String, Object> categoricalAttrs = new HashMap<>();
+
+    if (attributes != null) {
+      for (String key : attributes.keySet()) {
+        EppoValue value = attributes.get(key);
+        if (value != null && !value.isNull()) {
+          if (value.isNumeric()) {
+            numericAttrs.put(key, value.doubleValue());
+          } else if (value.isBoolean()) {
+            // Booleans should be serialized as native JSON booleans, not strings
+            categoricalAttrs.put(key, value.booleanValue());
+          } else {
+            categoricalAttrs.put(key, value.stringValue());
+          }
+        }
+      }
+    }
+
+    result.put("numericAttributes", numericAttrs);
+    result.put("categoricalAttributes", categoricalAttrs);
+    return result;
+  }
+}