Add nullability annotations to tests in module/spring-boot-jsonb

See gh-47263

Author: mhalbritter

module/spring-boot-jsonb/build.gradle

@@ -37,3 +37,7 @@ dependencies {
 
 testRuntimeOnly("ch.qos.logback:logback-classic")
 }
+
+tasks.named("compileTestJava") {
+options.nullability.checking = "tests"
+}