Completion of secondary class from current CU often generates import

Here's the example I'm currently working with. Open completion at the `|` and accept the result referring to `Outer.Inner`.

```java
package dev.datho7561.utils;

/**
* Outer.Inn|
*/
public class Main {

}
class Outer {
class Inner {
}
}
```

The same thing happens here if you accept `Outer.Inner`:

```java
package dev.datho7561.utils;

public class Main {
Inn|
}
class Outer {
class Inner {
}
}
```

I think this problem happens on the jdt.ui layer based on the test cases in jdt.core . (I don't think the `CompletionEngine` generates an import declaration required proposal).