Product Version = NetBeans IDE 8.0 (Build 201403101706)
Operating System = Linux version 3.11.0-18-generic running on amd64
Java; VM; Vendor = 1.8.0
Runtime = Java HotSpot(TM) 64-Bit Server VM 25.0-b70

Inspect and Transform -> JDK Migration -> Add underscores erroneously removed negative sign!

To reproduce: create a Java class 

public class TestConstants {

    public final long A = 123456789;
    public final long B = -123456789;

}

and perform the Transformation above. Gives :

public class TestConstants {

    public final long A = 123_456_789;
    public final long B = 123_456_789; // NOTE THE MISSING SIGN!!!!

}


But should be 

public class TestConstants {

    public final long A = 123_456_789;
    public final long B = -123_456_789; 

}