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What is the purpose of having a wrapper class for JarFile in Spring-boot-loader?

My question relates to [Spring-boot-loader v2.6.15](https://github.com/spring-projects/spring-boot/tree/v2.6.15/spring-boot-project/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/jar).

For the purposes of this question, I will refer to Spring's custom `JarFile` class as `CustomJarFile` to avoid confusion.

----

## Context

I am reusing some of the jar package code in spring-boot-loader. I noticed that they define their own [`CustomJarFile` implementation](https://github.com/spring-projects/spring-boot/blob/v2.6.15/spring-boot-project/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/jar/JarFile.java) that (most relevant to this question) overrides the `close()` method like so:

```
@Override
public void close() throws IOException {
	if (this.closed) {
		return;
	}
	super.close();
	if (this.type == JarFileType.DIRECT) {
		this.rootFile.close();
	}
	this.closed = true;
}
```

They also define a [`JarFileWrapper`](https://github.com/spring-projects/spring-boot/blob/v2.6.15/spring-boot-project/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/jar/JarFileWrapper.java) class that **does not** override the close method.

The custom [`JarUrlConnection#get()`](https://github.com/spring-projects/spring-boot/blob/v2.6.15/spring-boot-project/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/jar/JarURLConnection.java#L266) method notably returns an instance with the wrapper rather than the jar itself like so:

```
static JarURLConnection get(URL url, JarFile jarFile) throws IOException {
    // some stuff here...
    return new JarURLConnection(url, jarFile.getWrapper(), jarEntryName); // JarFile here is the custom class
}

```

Testing the code without the wrapper class by returning a `JarUrlConnection` with the `CustomJarFile` itself rather than its wrapper results in a "zip file closed" exception.

This is reasonable given that when you call `close()` on the wrapper, it will call the `close()` method of the `ZipFile` class. However, if the `JarFile` itself is sent, it will call the `close()` method of the `JarFile` since it is overriden.

Notably, The JavaDoc of the wrapper class states:

> A wrapper used to create a copy of a {@link CustomJarFile} so that it can be safely closed without closing the original.

----

## Question

I do not quite understand the purpose of using a wrapper here. If the goal is to just avoid closing the `CustomJarFile`, wouldn't simply not overriding the `close()` method in `CustomJarFile` (allowing it to propogate to `ZipFile`) have the same effect as using a wrapper? It feels like we just added a redundant layer.

While debugging, I've noticed that the `close()` method of `CustomJarFile` is never called between startup and shutdown of the service which makes me further believe that the wrapper is pointless if you simply remove the overriden close method in `CustomJarFile`.