Product Version: NetBeans IDE Dev (Build 20080328094427)
Java: 1.6.0_10-beta; Java HotSpot(TM) Client VM 11.0-b11
System: Windows XP version 5.1 running on x86; Cp1250; cs_CZ (nb)

Refactoring does not check method return type when changing type of field. It can produce uncompilable code.

Steps to reproduce:
1) have a class (Iface is empty interface):
public class Main implements Iface {

    static Main default;

    static Main getDefault() {
        return default;
    }
}

2) call User supertype on Main and select Iface

->

public class Main implements Iface {

    static Iface default;

    static Main getDefault() {
        return default;   // <---- not compatible types
    }
}