From 1d4609cde093fc6ecda6557774ac4e915060ab7e Mon Sep 17 00:00:00 2001
From: Tobias Ibounig <tobias.ibounig@dynatrace.com>
Date: Fri, 19 Jun 2026 09:34:57 +0200
Subject: [PATCH] perf: return ImmutableContext.EMPTY when merging two empty
 contexts

Signed-off-by: Tobias Ibounig <tobias.ibounig@dynatrace.com>
---
 .../dev/openfeature/sdk/ImmutableContext.java |  3 ++
 .../openfeature/sdk/ImmutableContextTest.java | 35 +++++++++++++++++++
 2 files changed, 38 insertions(+)

diff --git a/src/main/java/dev/openfeature/sdk/ImmutableContext.java b/src/main/java/dev/openfeature/sdk/ImmutableContext.java
index c8992db18..dd65538b8 100644
--- a/src/main/java/dev/openfeature/sdk/ImmutableContext.java
+++ b/src/main/java/dev/openfeature/sdk/ImmutableContext.java
@@ -88,6 +88,9 @@ public String getTargetingKey() {
     @Override
     public EvaluationContext merge(EvaluationContext overridingContext) {
         if (overridingContext == null || overridingContext.isEmpty()) {
+            if (this.isEmpty()) {
+                return ImmutableContext.EMPTY;
+            }
             return new ImmutableContext(this.asUnmodifiableMap());
         }
         if (this.isEmpty()) {
diff --git a/src/test/java/dev/openfeature/sdk/ImmutableContextTest.java b/src/test/java/dev/openfeature/sdk/ImmutableContextTest.java
index a365b6fc2..08744fc3e 100644
--- a/src/test/java/dev/openfeature/sdk/ImmutableContextTest.java
+++ b/src/test/java/dev/openfeature/sdk/ImmutableContextTest.java
@@ -253,6 +253,41 @@ void nullTargetingKeyWithNullAttributesYieldsEmptyContext() {
         }
     }
 
+    @Nested
+    @DisplayName("ImmutableContext.merge() empty short-circuit")
+    class MergeEmpty {
+
+        @Test
+        @DisplayName("merging two empty contexts returns the EMPTY singleton")
+        void mergingTwoEmptyContextsReturnsEmptySingleton() {
+            EvaluationContext result = new ImmutableContext().merge(new ImmutableContext());
+            assertThat(result).isSameAs(ImmutableContext.EMPTY);
+        }
+
+        @Test
+        @DisplayName("merging empty context with null returns the EMPTY singleton")
+        void mergingEmptyContextWithNullReturnsEmptySingleton() {
+            EvaluationContext result = new ImmutableContext().merge(null);
+            assertThat(result).isSameAs(ImmutableContext.EMPTY);
+        }
+
+        @Test
+        @DisplayName("merging non-empty context with null does not return EMPTY")
+        void mergingNonEmptyContextWithNullDoesNotReturnEmpty() {
+            EvaluationContext result = new ImmutableContext("key").merge(null);
+            assertThat(result).isNotSameAs(ImmutableContext.EMPTY);
+            assertThat(result.getTargetingKey()).isEqualTo("key");
+        }
+
+        @Test
+        @DisplayName("merging non-empty context with empty override does not return EMPTY")
+        void mergingNonEmptyContextWithEmptyOverrideDoesNotReturnEmpty() {
+            EvaluationContext result = new ImmutableContext("key").merge(new ImmutableContext());
+            assertThat(result).isNotSameAs(ImmutableContext.EMPTY);
+            assertThat(result.getTargetingKey()).isEqualTo("key");
+        }
+    }
+
     @Nested
     class Equals {
         ImmutableContext ctx = new ImmutableContext("c", Map.of("a", new Value("b")));