code: private static <T> T firstNotNull(T o1, T o2) {
  
          if (o1 != null) {
              return o1;
          }
          return o2;
      }
docs: Gets the fist non-null value.<p>
  
  @param o1 the first value
  @param o2 the second value
  
  @return the first non-null value