code: @Trivial
      private void stateHalfOpen() {
          halfOpenRunningExecutions = 0;
          halfOpenSuccessfulExecutions = 0;
          state.set(State.HALF_OPEN);
          metricRecorder.reportCircuitHalfOpen();
          if (TraceComponent.isAnyTracingEnabled() && tc.isDebugEnabled()) {
              Tr.debug(tc, "Transitioned to Half Open state");
          }
      }
docs: Transition to half open state