addAll for a collection of LongLists

The benefit is, that we only need one memory allocation.

primitiveCollections/src/main/java/org/lucares/collections/LongList.java

@@ -2,6 +2,7 @@ package org.lucares.collections;
 
 import java.io.Serializable;
 import java.util.Arrays;
+import java.util.Collection;
 import java.util.List;
 import java.util.Random;
 import java.util.Spliterator.OfLong;
@@ -380,6 +381,21 @@ public final class LongList implements Serializable, Cloneable {
 		size += list.size();
 	}
 
+	/**
+	 * Add all values of the given lists.
+	 * 
+	 * @param longLists collection of the lists
+	 * @throws NullPointerException if the collection of {@link LongList} is null or
+	 *                              contains null
+	 */
+	public void addAll(final Collection<LongList> longLists) {
+		final int sizeNewElements = longLists.stream().mapToInt(LongList::size).sum();
+		ensureCapacity(sizeNewElements);
+		for (final LongList longList : longLists) {
+			addAll(longList);
+		}
+	}
+
 	/**
 	 * Removes elements from the list.
 	 * <p>