code: @SuppressWarnings("unchecked")
      public static <T> Constructor<T> constructor(Class<T> declaringClass, Class<?>... parameterTypes) {
          return (Constructor<T>) WhiteboxImpl.findUniqueConstructorOrThrowException(declaringClass,
                  (Object[]) parameterTypes);
      }
docs: Returns a constructor specified in declaringClass.
  
  @param declaringClass
  The declaringClass of the class where the constructor is
  located.
  @param parameterTypes
  All parameter types of the constructor (may be
  {@code null}).
  @return A {@code java.lang.reflect.Constructor}.
  @throws ConstructorNotFoundException
  if the constructor cannot be found.