Hi in final test of this trailhead
https://trailhead.salesforce.com/content/learn/projects/automate-ordertocash-process-using-mulesoft-flow-designer

I get following error in design center from mulesoft

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Message               : HTTP POST on resource 'https://anypoint.mulesoft.com/mocking/api/v1/sources/exchange/assets/org.mule.examples/quick-start-nto-orders-api/1.0.0/m/orders' failed: bad request (400).
Element               : salesforce_to_twilio_connector/processors/3 @ ordertocashautomation-pqks:mule-config.xml:59 (Request)
Element XML           : <http:request config-ref="http_request" doc:id="6c2ef24f-8665-4ef0-90cf-ffc941e025c6" doc:name="Request" doc:timestamp="1571147129555" method="POST" url="https://anypoint.mulesoft.com/mocking/api/v1/sources/exchange/assets/org.mule.examples/quick-start-nto-orders-api/1.0.0/m/orders">
                        <http:body>#[%dw 2.0
                        output application/json---
                        null]</http:body>
                        </http:request>
Error type            : HTTP:BAD_REQUEST
FlowStack             : at salesforce_to_twilio_connector(salesforce_to_twilio_connector/processors/3 @ ordertocashautomation-pqks:mule-config.xml:59 (Request)) 218 ms
Payload Type          : org.mule.runtime.core.internal.streaming.bytes.ManagedCursorStreamProvider
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