public File merge() {
if (!f1.exists()) {
Log.logWarning("IODispatcher", "merge of file (1) " + f1.getName() + " failed: file does not exists");
return null;
}
<BUG>if (!f2.exists()) {
Log.logWarning("IODispatcher", "merge of file (2) " + f2.getName() + " failed: file does not exists");</BUG>
return null;
}
return array.mergeMount(f1, f2, factory, payloadrow, newFile, (int) Math.min(MemoryControl.available() / 3, writeBufferSize));

public File merge() {
if (!f1.exists()) {
Log.logWarning("IODispatcher", "merge of file (1) " + f1.getName() + " failed: file does not exists");
return null;
}
if (f2 != null && !f2.exists()) {
Log.logWarning("IODispatcher", "merge of file (2) " + f2.getName() + " failed: file does not exists");
return null;
}
return array.mergeMount(f1, f2, factory, payloadrow, newFile, (int) Math.min(MemoryControl.available() / 3, writeBufferSize));
