cglib | Byte Code Generation Library is high level API | Reflection library

Your mappings are incorrect - you'll need to look into JPA tutorials on how to map derived ids, but the error tells you what is wrong, pointing you at your ClassifiedGroup.interaction mapping(s). The PK class must use the Interaction's ID (a UUID), not the Interaction instance itself.

Since Java 9, Java introduced Modules and some frameworks such as Spring, rely on several Reflection behaviour and because of the modularization, some classes had their attribute not accessible through Reflection. The solution would be change the accessibility of these attributes, but it would take forever to do that.

The real solution is to add this VM option when you run your application: --add-opens java.base/java.lang=ALL-UNNAMED

Please refer to this great answer on another post with a similar problem: Answer to similar question

I changed your application to use Spring Boot, have you consider using it? For Spring applications, it is a very handy solution since it abstract many configurations. Here is a link with a detailed example: Spring Boot Example

From previous comments:

The unfound classes are dynamic proxies which are heavily used by the Spring Framework in order to implement AOP. Spring can use both JDK dynamic interface proxies and CGLIB proxies, the latter of which is what we are seeing here. Maybe you should simply ignore those types of classes. They are in fact created dynamically, hence the name. But they are rather a result of dynamic (sub-)class generation than of bytecode transformation.

Yes, I have considered just ignoring those dynamically generated classes, but the whole point of my application was to capture every single method invocation as a user interacts with the web application (such as clicking on a button, etc). In this case, would it be okay to ignore these types of dynamically generated classes? I want to make sure I do not miss any method calls.

As those classes are just dynamic proxies, they will either forward the calls to the original methods or call some AOP or interceptor logic first/instead. Either way, you would not miss anything essential, those proxies are more like switchboards or routers, the actual show happens somewhere else. I recommend you to simply try in a little playgrounds project with an aspect or two.

You also asked how to detect and ignore dynamic proxies by their names:

• CGLIB proxies: Spring's CGLIB proxies contain substrings like $$FastClassBySpringCGLIB$$ or $$EnhancerBySpringCGLIB$$, followed by 8 characters representing 4 hexadecimal bytes. You could either match with a regular expression of just keep it simple and match the substring BySpringCGLIB$$. If non-Spring CGLIB proxies are also in use somewhere in your application, you would have to watch for other naming patterns. But probably you would get similar errors as before when not filtering them, so you would notice automatically.

• JDK proxies: If your Spring application also happens to use JDK proxies, you can identify them easily using JRE API call Proxy.isProxyClass(Class). Thanks to Johannes Kuhn for his comment.

• JDK proxies (old answer): You can filter class names beginning with $Proxy, usually something like com.sun.proxy.$Proxy2 (the trailing number being different). According to the JDK documentation: "The unqualified name of a proxy class is unspecified. The space of class names that begin with the string "$Proxy" is, however, to be reserved for proxy classes." At least for Oracle and probably OpenJDK, you can match for that naming pattern. If that holds true for all JVMs, is up to you to test, if chances are that in your environments others are being used. I quickly tried with Semeru OpenJ9, and the proxy naming pattern is identical, even the package name com.sun.proxy. Pleasae note that in more recent JDK versions, JDK proxies will have fully qualified names like jdk.proxy2.$Proxy25, so in e.g. Java 16 or 17 you should not rely on package name com.sun.proxy. Either add more cases or limit matching to the leading $Proxy in the simple class name.

Update 2022-02-26: Because there was activity on this question, I decided to add some more information about Spring-specific tools which can determine whether an object (or a class) is an AOP proxy (class) and, more specifically, if it is a CGLIB or JDK proxy:

Take a look at tool class AopUtils and its handy methods

• isAopProxy(Object),
• isCglibProxy(Object),
• isJdkDynamicProxy(Object).

No more String matching, simply ask Spring.

BTW, there is also a method net.sf.cglib.proxy.Proxy.isProxyClass(Class) directly in CGLIB, which is supposed to do the same, but within Spring it does not work, probably because Spring uses CGLIB in a non-canonical way. Because Spring embeds a package-relocated CGLIB in its core, the corresponding method org.springframework.cglib.proxy.Proxy.isProxyClass(Class) yields the same faulty result. So if you are working within Spring, please do not use those methods, better use AopUtils.

Here is some example code for your convenience, showing how to determine Spring AOP proxy types (JDK vs. CGLIB proxies) using AopUtils. See also my answer here for how to configure Spring in order to use both proxy types.

BTW, instead of Javassist you could also use AspectJ for your purpose. It sounds like a pretty typical use case.

Spring 3.2.0.RELEASE uses asm 4.0, which does not support Java 8 or higher.

Since Java 7 is not supported any more, you should upgrade Spring to the latest patch release:

My access token was missing a scope called: "Calendars.ReadWrite". This is how that scope was supposed to be added.

The reason you see the NullPointerException is due to the default comparator used by the MultiResourceItemReader to sort the resources after loading them.

The default compare behavior calls the getFilename() method of the InputStreamResource.

Refer - https://github.com/spring-projects/spring-batch/blob/115c3022147692155d45e23cdd5cef84895bf9f5/spring-batch-infrastructure/src/main/java/org/springframework/batch/item/file/MultiResourceItemReader.java#L82

But the InputStreamResource just inherits the getFileName() method from its parent AbstractResource, which just returns null. https://github.com/spring-projects/spring-framework/blob/316e84f04f3dbec3ea5ab8563cc920fb21f49749/spring-core/src/main/java/org/springframework/core/io/AbstractResource.java#L220

The solution is to provide a custom comparator for the MultiResourceItemReader. Here is a simple example, assuming you do not want to sort the resources in a specific way before processing:

You might be hitting Spring issue #21674 which was fixed in Spring 5.1. You might want to upgrade, if that is an option. It seems there is a fix which ignores those kinds of methods. If that is OK for you or not, I do not know.

Some background information: Your target method is transactional, so Spring tries to create a CGLIB proxy for it. I quickly verified in a simple Spock (Groovy) test that CGLIB seems to be unable to handle methods containing spaces correctly -probably because it is simply unaware of languages like Groovy and Kotlin which allow such things. Here is a proof of concept. I used Groovy and Spock, because I am lazy and did not want to set up a Kotlin project. But I am expecting the result to be identical.

Java class under test:

Play 2.8 supports Java 8-11, I set my environmental variable "JAVA_HOME" to the Java 8 JDK and the command sbt run worked.

You are selecting a subset (start_rent_date and end_rent_date) of the columns of the table sweetholiday_user_house. However the results are being mapped to the managed entity SweetholidayUserHouse. So the mapping fails when it looks for the id column in the resultset, which is missing.

You can avoid this exception by either of these two approaches. There are several more. Here is a good discussion of this - Spring JPA selecting specific columns

Option 1: Keep the existing query and change the return type of the findAllReserved() method to Object[]. Here for each Object[], Object[0] is start_rent_date and Object[1] is end_rent_date.