code: public CircuitBreaker<R> withFailureThreshold(int failureThreshold) {
      Assert.isTrue(failureThreshold >= 1, "failureThreshold must be greater than or equal to 1");
      return withFailureThreshold(failureThreshold, failureThreshold);
    }
docs: Sets the number of successive failures that must occur when in a closed state in order to open the circuit.
  
  @throws IllegalArgumentException if {@code failureThresh} < 1