Change LeafNode clone to copy the properties instead of using getKey() constructor (RoaringBitmap#825)

* Change LeafNode clone to copy the properties instead of using constructor

* better clone

Author: hmedlinphocas

roaringbitmap/src/main/java/org/roaringbitmap/art/LeafNode.java

@@ -43,8 +43,8 @@ public LeafNode(long key, long containerIdx) {
   }
 
   @Override
-  protected LeafNode clone() {
-    return new LeafNode(getKey(), containerIdx);
+  public LeafNode clone() {
+    return new LeafNode(getKey() << 16, containerIdx);
   }
 
   @Override
@@ -99,14 +99,14 @@ public byte[] getKeyBytes() {
   }
 
   public long getKey() {
-    return (((long) keyHigh) & 0xFFFFFFFFL) << 16 | (((long)keyLow) & 0xFFFFL);
+    return (((long) keyHigh) & 0xFFFFFFFFL) << 16 | (((long) keyLow) & 0xFFFFL);
   }
 
-    /**
-     * Sets the key from a long value, only the high 48 bits are used.
-     *
-     * @param key the long value representing the key
-     */
+  /**
+   * Sets the key from a long value, only the high 48 bits are used.
+   *
+   * @param key the long value representing the key
+   */
   private void setKeyFromShifted(long key) {
     this.keyHigh = (int) (key >> 32);
     this.keyLow = (char) (key >> 16);
@@ -124,16 +124,17 @@ protected void serializeHeader(DataOutput dataOutput) throws IOException {
   @Override
   protected void serializeHeader(ByteBuffer byteBuffer) throws IOException {
     byteBuffer.put((byte) NodeType.LEAF_NODE.ordinal());
-    byteBuffer.putShort((short)0);
-    byteBuffer.put((byte)0);
+    byteBuffer.putShort((short) 0);
+    byteBuffer.put((byte) 0);
   }
 
   @Override
   public String toString() {
-    return "LeafNode{" +
-            "key=" + Long.toHexString(getKey()) +
-            ", containerIdx=" + containerIdx +
-            '}';
+    return "LeafNode{"
+        + "key="
+        + Long.toHexString(getKey())
+        + ", containerIdx="
+        + containerIdx
+        + '}';
   }
-
 }

roaringbitmap/src/test/java/org/roaringbitmap/art/LeafNodeTest.java

@@ -0,0 +1,15 @@
+package org.roaringbitmap.art;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+public class LeafNodeTest {
+
+  @Test
+  public void testClone() {
+    LeafNode leafOne = new LeafNode(new byte[] {1, 2, 3, 4, 5, 0}, 10);
+    LeafNode cloned = leafOne.clone();
+
+    Assertions.assertEquals(leafOne.toString(), cloned.toString());
+  }
+}