@Override
  @SuppressWarnings("unchecked")
  public <T> T[] toArray(T[] a) {
    fullyLock();
    try {
      int size = count.get();
      if (a.length < size) {
        a = (T[]) java.lang.reflect.Array.newInstance(a.getClass().getComponentType(), size);
      }

      int k = 0;
      for (Node<E> p = head.next; p != null; p = p.next) {
        a[k++] = (T) p.item;
      }
      if (a.length > k) {
        a[k] = null;
      }
      return a;
    } finally {
      fullyUnlock();
    }
  }
Returns an array containing all of the elements in this queue, in proper sequence; the runtime
type of the returned array is that of the specified array. If the queue fits in the specified
array, it is returned therein. Otherwise, a new array is allocated with the runtime type of the
specified array and the size of this queue.

<p>
If this queue fits in the specified array with room to spare (i.e., the array has more elements
than this queue), the element in the array immediately following the end of the queue is set to
{@code null}.

<p>
Like the {@link #toArray()} method, this method acts as bridge between array-based and
collection-based APIs. Further, this method allows precise control over the runtime type of the
output array, and may, under certain circumstances, be used to save allocation costs.

<p>
Suppose {@code x} is a queue known to contain only strings. The following code can be used to
dump the queue into a newly allocated array of {@code String}:

<pre>
String[] y = x.toArray(new String[0]);
</pre>

Note that {@code toArray(new Object[0])} is identical in function to {@code toArray()}.

@param a the array into which the elements of the queue are to be stored, if it is big enough;
       otherwise, a new array of the same runtime type is allocated for this purpose
@return an array containing all of the elements in this queue
@throws ArrayStoreException if the runtime type of the specified array is not a supertype of
        the runtime type of every element in this queue
@throws NullPointerException if the specified array is null
geode-core/src/main/java/org/apache/geode/internal/cache/ForceableLinkedBlockingQueue.java