Replace class in file with new implementation

I'm currently trying to implement a Class-to-Record Transformation POC using spoon.
It is almost done and works pretty well, the only issue I have is with bringing the modified code back as a prittyprinted string.

```kotlin
SniperJavaPrettyPrinter(env).printCompilationUnit(cu)
```
works in general but has weird spaces at the beginning (which can be removed with `trim()`) and messes up the newlines for imports and the class.

```java
import lombok.Getter;public record ....
```
instead of:
```java
import lombok.Getter;

public record ....
```

Using `prettyprint()` directly, messes up the order and style of surrounding comments.

```java
/* .before */
// .after
record Person(String firstName, String lastName) {
public String name() {
return (firstName + " ") + lastName;
}
}
```
instead of:
```java
// .before
record Person(String firstName, String lastName) {
public String name() {
return firstName + " " + lastName;
}
}
// .after
```

I replace the class by calling `class.replace(record)` and copying the `position` and `parent` direct from the class to the record.

Do I miss something or have I misunderstood the replace function or the way one does refactroings with spoon?

Any help is appreciated.