code: private Object[] _asArray(
                      final Object obj
                      )
      {
          Object[]  array = null;
          if (obj instanceof Object[]) {
              array = (Object[])obj;
              if (array.length == 0) {
                  throw new IllegalArgumentException( "ERROR: empty array" );
              }
          } else {
              array = new Object[] { obj };
          }
  
          return array;
      }
docs: Converts the type of specified object to array.
  If the type of the object is array, it is simply casted.
  Otherwise, an unary array that contains only the specified object
  is created.