Add nullability annotations to tests in module/spring-boot-groovy-templates

See gh-47263

module/spring-boot-groovy-templates/build.gradle

@@ -40,3 +40,7 @@ dependencies {
 
 	testRuntimeOnly("ch.qos.logback:logback-classic")
 }
+
+tasks.named("compileTestJava") {
+	options.nullability.checking = "tests"
+}

module/spring-boot-groovy-templates/src/test/java/org/springframework/boot/groovy/template/autoconfigure/GroovyTemplateAutoConfigurationTests.java

@@ -29,6 +29,7 @@ import groovy.text.markup.DelegatingIndentWriter;
 import groovy.text.markup.MarkupTemplateEngine;
 import groovy.text.markup.TemplateConfiguration;
 import jakarta.servlet.http.HttpServletRequest;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
@@ -320,7 +321,7 @@ class GroovyTemplateAutoConfigurationTests {
 		}
 
 		@Override
-		public Object run() {
+		public @Nullable Object run() {
 			return null;
 		}