Nway throws a null pointer exception every time

[mausotog]

Hi, I am trying to run the nway mode, but everytime I run it with any code it shows a null pointer exception.
As a minimal example I created 3 classes. Class1.java contains the following code.
public class Class1{
public int method1(){
return 1;
}
}
Class2.java and Class3.java are similar but returning values "2" and "3" accordingly.

I tried to use JDime to merge them using the following command:
../jdime//build/install/JDime/bin/JDime --mode nway -f --output ClassExit.java Class1.java Class2.java Class3.java

But everytime I get an error as follows:
Logging configuration file JDimeLogging.properties does not exist. Falling back to defaults.
JDime [18:46:17] WARNING: JDime.properties can not be used as a config file as it does not exist.
JDime [18:46:17] SEVERE: Exception while merging:
JDime [18:46:17] SEVERE: A: Class1.java
JDime [18:46:17] SEVERE: B: Class2.java
JDime [18:46:17] SEVERE: C: Class3.java
JDime [18:46:17] SEVERE: java.lang.NullPointerException
JDime [18:46:17] SEVERE: Uncaught exception.
java.lang.Error: java.lang.NullPointerException
at de.fosd.jdime.strategy.NWayStrategy.merge(NWayStrategy.java:149)
at de.fosd.jdime.artifact.file.FileArtifact.merge(FileArtifact.java:647)
at de.fosd.jdime.operations.MergeOperation.apply(MergeOperation.java:166)
at de.fosd.jdime.Main.merge(Main.java:446)
at de.fosd.jdime.Main.run(Main.java:156)
at de.fosd.jdime.Main.main(Main.java:113)
Caused by: java.lang.NullPointerException
at de.fosd.jdime.merge.Merge.merge(Merge.java:73)
at de.fosd.jdime.artifact.ast.ASTNodeArtifact.merge(ASTNodeArtifact.java:471)
at de.fosd.jdime.operations.MergeOperation.apply(MergeOperation.java:166)
at de.fosd.jdime.strategy.NWayStrategy.merge(NWayStrategy.java:109)
... 5 more

I have also tried with 4 classes. Same error.
This error does not happen with Linebased or Structured modes.

Thanks in advance for the help.