Polishing contribution

Closes gh-33150

Author: rstoyanchev

spring-context/src/main/java/org/springframework/validation/beanvalidation/MethodValidationAdapter.java

@@ -50,7 +50,6 @@
 import org.springframework.core.ParameterNameDiscoverer;
 import org.springframework.core.annotation.AnnotationUtils;
 import org.springframework.lang.Nullable;
-import org.springframework.util.Assert;
 import org.springframework.util.function.SingletonSupplier;
 import org.springframework.validation.BeanPropertyBindingResult;
 import org.springframework.validation.BindingResult;
@@ -321,7 +320,7 @@ else if (node.getKind().equals(ElementKind.RETURN_VALUE)) {
 
 				Object arg = argumentFunction.apply(parameter.getParameterIndex());
 
-				// If the arg is a container, we need to element, but the only way to extract it
+				// If the arg is a container, we need the element, but the only way to extract it
 				// is to check for and use a container index or key on the next node:
 				// https://github.com/jakartaee/validation/issues/194
 
@@ -346,16 +345,16 @@ else if (key != null && arg instanceof Map<?, ?> map) {
 					value = map.get(key);
 					container = map;
 				}
-				else if (arg instanceof Set<?>) {
+				else if (arg instanceof Iterable<?>) {
+					// No index or key, cannot access the specific value
 					value = arg;
-					container = null;
+					container = arg;
 				}
 				else if (arg instanceof Optional<?> optional) {
 					value = optional.orElse(null);
 					container = optional;
 				}
 				else {
-					Assert.state(!node.isInIterable(), "No way to unwrap Iterable without index");
 					value = arg;
 					container = null;
 				}

spring-context/src/test/java/org/springframework/validation/beanvalidation/MethodValidationAdapterTests.java

@@ -40,7 +40,6 @@
 import org.springframework.validation.method.ParameterValidationResult;
 
 import static org.assertj.core.api.Assertions.assertThat;
-import static org.assertj.core.api.InstanceOfAssertFactories.SET;
 
 /**
  * Tests for {@link MethodValidationAdapter}.
@@ -203,9 +202,7 @@ void validateValueListArgument() {
 		Method method = getMethod(target, "addHobbies");
 
 		testArgs(target, method, new Object[] {List.of("   ")}, ex -> {
-
 			assertThat(ex.getAllValidationResults()).hasSize(1);
-
 			assertValueResult(ex.getValueResults().get(0), 0, "   ", List.of("""
 				org.springframework.context.support.DefaultMessageSourceResolvable: \
 				codes [NotBlank.myService#addHobbies.hobbies,NotBlank.hobbies,NotBlank.java.util.List,NotBlank]; \
@@ -215,15 +212,13 @@ void validateValueListArgument() {
 		});
 	}
 
-	@Test
+	@Test // gh-33150
 	void validateValueSetArgument() {
 		MyService target = new MyService();
 		Method method = getMethod(target, "addUniqueHobbies");
 
 		testArgs(target, method, new Object[] {Set.of("test", "   ")}, ex -> {
-
 			assertThat(ex.getAllValidationResults()).hasSize(1);
-
 			assertValueResult(ex.getValueResults().get(0), 0, Set.of("test", "   "), List.of("""
 				org.springframework.context.support.DefaultMessageSourceResolvable: \
 				codes [NotBlank.myService#addUniqueHobbies.hobbies,NotBlank.hobbies,NotBlank.java.util.Set,NotBlank]; \