From cb61d0687b08eb661286452241338b6652cd8170 Mon Sep 17 00:00:00 2001
From: Hardik Singh Behl <hardik.behl7444@gmail.com>
Date: Wed, 2 Sep 2026 18:34:01 +0530
Subject: [PATCH 1/3] BAEL-9752: add UT

---
 .../java8/lambda/exceptions/RecordStream.java | 13 +++++++++++++
 .../java8/lambda/exceptions/Validator.java    | 11 +++++++++++
 .../LambdaWildcardInferenceUnitTest.java      | 19 +++++++++++++++++++
 3 files changed, 43 insertions(+)
 create mode 100644 core-java-modules/core-java-lambdas/src/main/java/com/baeldung/java8/lambda/exceptions/RecordStream.java
 create mode 100644 core-java-modules/core-java-lambdas/src/main/java/com/baeldung/java8/lambda/exceptions/Validator.java
 create mode 100644 core-java-modules/core-java-lambdas/src/test/java/com/baeldung/java8/lambda/exceptions/LambdaWildcardInferenceUnitTest.java

diff --git a/core-java-modules/core-java-lambdas/src/main/java/com/baeldung/java8/lambda/exceptions/RecordStream.java b/core-java-modules/core-java-lambdas/src/main/java/com/baeldung/java8/lambda/exceptions/RecordStream.java
new file mode 100644
index 000000000000..52880f054919
--- /dev/null
+++ b/core-java-modules/core-java-lambdas/src/main/java/com/baeldung/java8/lambda/exceptions/RecordStream.java
@@ -0,0 +1,13 @@
+package com.baeldung.java8.lambda.exceptions;
+
+class RecordStream<E> {
+
+    static <T> RecordStream<T> create() {
+        return new RecordStream<>();
+    }
+
+    RecordStream<E> validate(Validator<? super E> validator) {
+        return this;
+    }
+
+}
\ No newline at end of file
diff --git a/core-java-modules/core-java-lambdas/src/main/java/com/baeldung/java8/lambda/exceptions/Validator.java b/core-java-modules/core-java-lambdas/src/main/java/com/baeldung/java8/lambda/exceptions/Validator.java
new file mode 100644
index 000000000000..95e0390ece45
--- /dev/null
+++ b/core-java-modules/core-java-lambdas/src/main/java/com/baeldung/java8/lambda/exceptions/Validator.java
@@ -0,0 +1,11 @@
+package com.baeldung.java8.lambda.exceptions;
+
+import java.util.function.Predicate;
+
+@FunctionalInterface
+interface Validator<T> extends Predicate<T> {
+
+    @Override
+    boolean test(T t);
+
+}
\ No newline at end of file
diff --git a/core-java-modules/core-java-lambdas/src/test/java/com/baeldung/java8/lambda/exceptions/LambdaWildcardInferenceUnitTest.java b/core-java-modules/core-java-lambdas/src/test/java/com/baeldung/java8/lambda/exceptions/LambdaWildcardInferenceUnitTest.java
new file mode 100644
index 000000000000..ff066ebf83ee
--- /dev/null
+++ b/core-java-modules/core-java-lambdas/src/test/java/com/baeldung/java8/lambda/exceptions/LambdaWildcardInferenceUnitTest.java
@@ -0,0 +1,19 @@
+package com.baeldung.java8.lambda.exceptions;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import org.junit.jupiter.api.Test;
+
+class LambdaWildcardInferenceUnitTest {
+
+    @Test
+    void whenImplicitlyTypedLambdaPassedToWildcardParameter_thenSuccess() {
+        Validator<? super Boolean> validator = b -> b;
+        RecordStream<Boolean> stream = RecordStream.<Boolean> create()
+            .validate(b -> b);
+
+        assertTrue(validator.test(true));
+        assertFalse(validator.test(false));
+    }
+}
\ No newline at end of file

From 0012d42a954b92659372dd4a002a364b8aeef203 Mon Sep 17 00:00:00 2001
From: Hardik Singh Behl <hardik.behl7444@gmail.com>
Date: Wed, 2 Sep 2026 18:37:36 +0530
Subject: [PATCH 2/3] update indentation

---
 .../java/com/baeldung/java8/lambda/exceptions/RecordStream.java  | 1 -
 .../java/com/baeldung/java8/lambda/exceptions/Validator.java     | 1 -
 2 files changed, 2 deletions(-)

diff --git a/core-java-modules/core-java-lambdas/src/main/java/com/baeldung/java8/lambda/exceptions/RecordStream.java b/core-java-modules/core-java-lambdas/src/main/java/com/baeldung/java8/lambda/exceptions/RecordStream.java
index 52880f054919..faa8e2ae838d 100644
--- a/core-java-modules/core-java-lambdas/src/main/java/com/baeldung/java8/lambda/exceptions/RecordStream.java
+++ b/core-java-modules/core-java-lambdas/src/main/java/com/baeldung/java8/lambda/exceptions/RecordStream.java
@@ -9,5 +9,4 @@ static <T> RecordStream<T> create() {
     RecordStream<E> validate(Validator<? super E> validator) {
         return this;
     }
-
 }
\ No newline at end of file
diff --git a/core-java-modules/core-java-lambdas/src/main/java/com/baeldung/java8/lambda/exceptions/Validator.java b/core-java-modules/core-java-lambdas/src/main/java/com/baeldung/java8/lambda/exceptions/Validator.java
index 95e0390ece45..bad5f788be3a 100644
--- a/core-java-modules/core-java-lambdas/src/main/java/com/baeldung/java8/lambda/exceptions/Validator.java
+++ b/core-java-modules/core-java-lambdas/src/main/java/com/baeldung/java8/lambda/exceptions/Validator.java
@@ -7,5 +7,4 @@ interface Validator<T> extends Predicate<T> {
 
     @Override
     boolean test(T t);
-
 }
\ No newline at end of file

From 2b20190c9e19b5dd31b032c8b79df6edeaae0a64 Mon Sep 17 00:00:00 2001
From: Hardik Singh Behl <hardik.behl7444@gmail.com>
Date: Fri, 4 Sep 2026 15:03:11 +0530
Subject: [PATCH 3/3] incorporate feedback

---
 .../baeldung/java8/lambda/exceptions/RecordStream.java | 10 +++-------
 .../exceptions/LambdaWildcardInferenceUnitTest.java    |  8 ++------
 2 files changed, 5 insertions(+), 13 deletions(-)

diff --git a/core-java-modules/core-java-lambdas/src/main/java/com/baeldung/java8/lambda/exceptions/RecordStream.java b/core-java-modules/core-java-lambdas/src/main/java/com/baeldung/java8/lambda/exceptions/RecordStream.java
index faa8e2ae838d..24ff8b69e810 100644
--- a/core-java-modules/core-java-lambdas/src/main/java/com/baeldung/java8/lambda/exceptions/RecordStream.java
+++ b/core-java-modules/core-java-lambdas/src/main/java/com/baeldung/java8/lambda/exceptions/RecordStream.java
@@ -1,12 +1,8 @@
 package com.baeldung.java8.lambda.exceptions;
 
-class RecordStream<E> {
+class RecordStream {
 
-    static <T> RecordStream<T> create() {
-        return new RecordStream<>();
-    }
-
-    RecordStream<E> validate(Validator<? super E> validator) {
-        return this;
+    static <E> boolean validate(E record, Validator<? super E> validator) {
+        return validator.test(record);
     }
 }
\ No newline at end of file
diff --git a/core-java-modules/core-java-lambdas/src/test/java/com/baeldung/java8/lambda/exceptions/LambdaWildcardInferenceUnitTest.java b/core-java-modules/core-java-lambdas/src/test/java/com/baeldung/java8/lambda/exceptions/LambdaWildcardInferenceUnitTest.java
index ff066ebf83ee..9f5259cc77d8 100644
--- a/core-java-modules/core-java-lambdas/src/test/java/com/baeldung/java8/lambda/exceptions/LambdaWildcardInferenceUnitTest.java
+++ b/core-java-modules/core-java-lambdas/src/test/java/com/baeldung/java8/lambda/exceptions/LambdaWildcardInferenceUnitTest.java
@@ -9,11 +9,7 @@ class LambdaWildcardInferenceUnitTest {
 
     @Test
     void whenImplicitlyTypedLambdaPassedToWildcardParameter_thenSuccess() {
-        Validator<? super Boolean> validator = b -> b;
-        RecordStream<Boolean> stream = RecordStream.<Boolean> create()
-            .validate(b -> b);
-
-        assertTrue(validator.test(true));
-        assertFalse(validator.test(false));
+        assertTrue(RecordStream.validate(Boolean.TRUE, b -> b));
+        assertFalse(RecordStream.validate(Boolean.FALSE, b -> b));
     }
 }
\ No newline at end of file