java.util.prefs.Preferences getByteArray(String key, byte[] def)

NullPointerException not thrown when key =null

Test program :
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import java.util.prefs.*;
import java.util.*;
 

public class GetByteArrayTest {
    public static void main(String[] args) throws Exception {
   
      try {
           Preferences userRoot = Preferences.userRoot();
           Preferences N1 = userRoot.node("N1");
           N1.clear();
          
           byte [] value = new byte[1];
           value[0]=(byte)2;
           N1.putByteArray("k1",value);
           byte[] valueExpected = value;
           byte[] valuedefault = new byte[1];
           valuedefault[0] = (byte)0;
           byte[] valueGot = N1.getByteArray(null,valuedefault);
           System.out.println("NullPointerException not thrown valueGot[0] = " + valueGot[0]);
      } catch(NullPointerException npe) {
          System.out.println("Expected NullPointerException thrown = " + npe);
          System.out.println("GetByteArrayTestTest02() Pass");
      } catch(Exception e) {
          System.out.println("Exception thrown = " + e);
          System.out.println("GetByteArrayTestTest02() Fail");
          e.printStackTrace();
      }
    }
 
}