code: public static <T> T[] removeDuplicates(final T[] a) {
          if (N.isNullOrEmpty(a)) {
              return a;
          }
  
          return removeDuplicates(a, false);
      }
docs: <p>
  Removes all duplicates elements
  </p>
  
  <pre>
  N.removeElements(["a", "b", "a"]) = ["a", "b"]
  </pre>
  
  @param <T>
  the component type of the array
  @param a
  @return A new array containing the existing elements except the duplicates
  
  @throws NullPointerException if the specified array <code>a</code> is null.