provider.get()

        then: "beforeValueObtained callback is notified"
        1 * computationListener.beforeValueObtained()

        then: "afterValueObtained callback is notified"
        1 * computationListener.afterValueObtained()

        then: "valueObtained is notified"
        obtainedValues.size() == 1
        obtainedValues[0].valueSourceType == EchoValueSource

     * {@link ValueListener#valueObtained(ValueListener.ObtainedValue, ValueSource)}.
     */
    @EventScope(Scope.Build.class)
    interface ComputationListener {
        void beforeValueObtained();

        void afterValueObtained();
    }

    @EventScope(Scope.Build.class)
    interface ValueListener {
        <T, P extends ValueSourceParameters> void valueObtained(
            ObtainedValue<T, P> obtainedValue,

                        sourceRef.set(source);
                        return source.obtain();
                    } finally {
                        computationBroadcaster.getSource().afterValueObtained();
                    }
                }
            );
        }

        public boolean hasBeenObtained() {
            return value.isFinalized();
        }

    override fun beforeValueObtained() {
        // Do not track additional inputs while computing a value of the value source.
        inputTrackingState.disableForCurrentThread()
    }

    override fun afterValueObtained() {
        inputTrackingState.restoreForCurrentThread()
    }

    override fun <T : Any, P : ValueSourceParameters> valueObtained(