code: public static Class<?> mostSpecificClass(Class<?> classOne,
                                               Class<?> classTwo)
      {
          if (classOne.isAssignableFrom(classTwo)) {
              return classTwo; // d479669
          }
          else if (classTwo.isAssignableFrom(classOne)) {
              return classOne; // d479669
          }
  
          return null;
      }
docs: Returns the most most specific class to the caller. If the two
  classes are not compatible a null is returned.
  
  @param classOne Class type of the method or field
  @param classTwo Class type of object being injected