code: @SuppressWarnings("unchecked")
      public static <T> Constructor<T> defaultConstructorIn(Class<T> declaringClass) {
          return (Constructor<T>) WhiteboxImpl.findDefaultConstructorOrThrowException(declaringClass);
      }
docs: Returns the default constructor in {@code declaringClass}
  
  @param declaringClass
  The declaringClass of the class where the constructor is
  located.
  @return A {@code java.lang.reflect.Constructor}.
  @throws ConstructorNotFoundException
  If no default constructor was found in  {@code declaringClass}