Properly handle `null` package

Closes gh-9621

spring-boot/src/main/java/org/springframework/boot/context/properties/ConfigurationPropertiesBindingPostProcessor.java

@@ -420,7 +420,8 @@ public class ConfigurationPropertiesBindingPostProcessor implements BeanPostProc
 			if (AnnotatedElementUtils.hasAnnotation(type, Validated.class)) {
 				return true;
 			}
-			if (type.getPackage().getName().startsWith("org.springframework.boot")) {
+			if (type.getPackage() != null &&
+					type.getPackage().getName().startsWith("org.springframework.boot")) {
 				return false;
 			}
 			if (getConstraintsForClass(type).isBeanConstrained()) {