Guard against instantiation errors in ValidationHelper

Prior to this commit, the `ValidationHelper` would fetch a `Validator`
implementation from the application context and unwrap it if necessary
in `createIfValidatorPresent`. This strategy can fail in the case of a
`OptionalLocalValidatorFactoryBean` bean when unwrapping, if the jakarta
validation API is on the classpath but no concrete provider is present.

This commit ensures that exceptions thrown during the unwrapping phase
are ignored and a `null` `ValidationHelper` is returned for those cases.

Fixes gh-1407

Author: bclozel

spring-graphql/src/main/java/org/springframework/graphql/data/method/annotation/support/ValidationHelper.java

@@ -119,11 +119,16 @@ else if (annot.annotationType().equals(Validated.class)) {
 	 */
 	static @Nullable ValidationHelper createIfValidatorPresent(ApplicationContext context) {
 		Validator validator = context.getBeanProvider(Validator.class).getIfAvailable();
-		if (validator instanceof LocalValidatorFactoryBean) {
-			validator = ((LocalValidatorFactoryBean) validator).getValidator();
+		try {
+			if (validator instanceof LocalValidatorFactoryBean) {
+				validator = ((LocalValidatorFactoryBean) validator).getValidator();
+			}
+			else if (validator instanceof SpringValidatorAdapter) {
+				validator = validator.unwrap(Validator.class);
+			}
 		}
-		else if (validator instanceof SpringValidatorAdapter) {
-			validator = validator.unwrap(Validator.class);
+		catch (Exception exc) {
+			return null;
 		}
 		return (validator != null) ? create(validator) : null;
 	}

spring-graphql/src/test/java/org/springframework/graphql/data/method/annotation/support/ValidationHelperTests.java

@@ -36,12 +36,16 @@
 import org.junit.jupiter.api.Test;
 
 import org.springframework.beans.BeanUtils;
+import org.springframework.context.support.StaticApplicationContext;
 import org.springframework.graphql.data.ArgumentValue;
 import org.springframework.graphql.data.method.HandlerMethod;
 import org.springframework.validation.annotation.Validated;
+import org.springframework.validation.beanvalidation.OptionalValidatorFactoryBean;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.mockito.BDDMockito.given;
+import static org.mockito.Mockito.mock;
 
 /**
  * Unit tests for {@link ValidationHelper}.
@@ -55,6 +59,15 @@ void shouldFailWithNullValidator() {
 		assertThatThrownBy(() -> ValidationHelper.create(null)).isInstanceOf(IllegalArgumentException.class);
 	}
 
+	@Test
+	void shouldReturnNullValidatorWhenInstantiationFailure() {
+		OptionalValidatorFactoryBean validatorFactory = mock(OptionalValidatorFactoryBean.class);
+		given(validatorFactory.getValidator()).willThrow(new IllegalStateException("No target ValidatorFactory set"));
+		StaticApplicationContext applicationContext = new StaticApplicationContext();
+		applicationContext.registerBean(Validator.class, () -> validatorFactory);
+		assertThat(ValidationHelper.createIfValidatorPresent(applicationContext)).isNull();
+	}
+
 	@Test
 	void shouldIgnoreMethodsWithoutAnnotations() {
 		assertThat(validateFunction(MyBean.class, "notValidatedMethod")).isNull();