Clean up "Use Multi-catch" does not removed then unused imports

If one applies the clean-up "Use Multi-catch" to the following code snippets, the afterwards unused import for `IOException` is not removed:
```
package test;
import java.io.IOException;

public class Test {
public void m() {
try {
m1();
} catch (IOException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
}
private void m1() throws Exception {
}
}
```
Expected is the following code, but at the moment the import is not removed.
```
package test;
public class Test {
public void m() {
try {
m1();
} catch (Exception e) {
e.printStackTrace();
}
}
private void m1() throws Exception {
}
}
```
The example makes a bit more sense when the called method is defined in another Class and lists both `IOException` and `Exception` in its throws list.

Reproduce the issue using the Java snippets in the report and apply the “Use Multi-catch” cleanup. Compare the result with the expected code: the redundant catch should be removed and the now-unused IOException import should also disappear.

Written by the indexing model from the issue text.