code: public CircuitBreaker<R> withSuccessThreshold(int successThreshold) {
      Assert.isTrue(successThreshold >= 1, "successThreshold must be greater than or equal to 1");
      return withSuccessThreshold(successThreshold, successThreshold);
    }
docs: Sets the number of successive successful executions that must occur when in a half-open state in order to close the
  circuit, else the circuit is re-opened when a failure occurs.
  
  @throws IllegalArgumentException if {@code successThreshold} < 1