codebase/bad-return-type-lambda-bug [BAEL-9752] [Improvement]

core-java-modules/core-java-lambdas/src/main/java/com/baeldung/java8/lambda/exceptions/RecordStream.java

@@ -0,0 +1,8 @@
+package com.baeldung.java8.lambda.exceptions;
+
+class RecordStream {
+
+    static <E> boolean validate(E record, Validator<? super E> validator) {
+        return validator.test(record);
+    }
+}

core-java-modules/core-java-lambdas/src/main/java/com/baeldung/java8/lambda/exceptions/Validator.java

@@ -0,0 +1,10 @@
+package com.baeldung.java8.lambda.exceptions;
+
+import java.util.function.Predicate;
+
+@FunctionalInterface
+interface Validator<T> extends Predicate<T> {
+
+    @Override
+    boolean test(T t);
+}

core-java-modules/core-java-lambdas/src/test/java/com/baeldung/java8/lambda/exceptions/LambdaWildcardInferenceUnitTest.java

@@ -0,0 +1,15 @@
+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() {
+        assertTrue(RecordStream.validate(Boolean.TRUE, b -> b));
+        assertFalse(RecordStream.validate(Boolean.FALSE, b -> b));
+    }
+}