Add new line to custom Exception message in Anypoint Studio Mule - mule

Question

I am using Anypoint Studio 6.1 and Mule 3.8.1 and want to return an Exception message with the "\n" returned as a new line. I am trying to use System.getProperty("line.separator") but the "\n" still appear in the message as text and not a new line.
How can I get this to work?
XML Test Flow:
<?xml version="1.0" encoding="UTF-8"?>
<mule xmlns:http="http://www.mulesoft.org/schema/mule/http" xmlns="http://www.mulesoft.org/schema/mule/core" xmlns:doc="http://www.mulesoft.org/schema/mule/documentation"
xmlns:spring="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-current.xsd
http://www.mulesoft.org/schema/mule/core http://www.mulesoft.org/schema/mule/core/current/mule.xsd
http://www.mulesoft.org/schema/mule/http http://www.mulesoft.org/schema/mule/http/current/mule-http.xsd">
<flow name="tempflowFlow">
<http:listener config-ref="HTTP_Listener_Configuration" path="/test-flow" allowedMethods="GET" doc:name="HTTP"/>
<set-payload value="{
"Exception": {
"status": -1,
"description": "\nJson content is not compliant with schema\ncom.github.fge.jsonschema.core.report.ListProcessingReport: failure\n--- BEGIN MESSAGES ---\nerror: object has too many properties (found 2 but schema requires at most 1)\n level: \"error\"\n schema: {\"loadingURI\":\"file:/C:/temp.json#\",\"pointer\":\"/properties/field1\"}\n instance: {\"pointer\":\"/field1\"}\n domain: \"validation\"\n keyword: \"maxProperties\"\n found: 2\n required: 1\n--- END MESSAGES ---\n (org.mule.module.json.validation.JsonSchemaValidationException)."
}
}" encoding="UTF-8" mimeType="application/json" doc:name="Set Payload"/>
<logger message="#[payload.replace("\n", System.getProperty('line.separator'))]" level="INFO" doc:name="Logger"/>
<set-payload value="#[payload.replace("\n", System.getProperty('line.separator'))]" encoding="UTF-8" mimeType="application/json" doc:name="Set Payload"/>
</flow>
</mule>
Thanks

Answer 1

Looks like you need to escape the newline character. Also, use single quotes (') instead of double quotes (") inside MEL expression.
<logger message="#[payload.replace('\\n', System.getProperty('line.separator'))]" level="INFO"
doc:name="Logger" />
<set-payload value="#[payload.replace('\\n', System.getProperty('line.separator'))]" encoding="UTF-8"
mimeType="application/json" doc:name="Set Payload" />
Above code seems to work:
INFO 2017-02-09 18:03:09,349 [Mule.app.deployer.monitor.1.thread.1] org.mule.module.launcher.MuleDeploymentService:
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+ Started app 'test2' +
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
INFO 2017-02-09 18:03:17,280 [[test2].HTTP_Listener_Configuration.worker.01] org.mule.api.processor.LoggerMessageProcessor: { "Exception": { "status": -1, "description": "
Json content is not compliant with schema
com.github.fge.jsonschema.core.report.ListProcessingReport: failure
--- BEGIN MESSAGES ---
error: object has too many properties (found 2 but schema requires at most 1)
level: \"error\"
schema: {\"loadingURI\":\"file:/C:/temp.json#\",\"pointer\":\"/properties/field1\"}
instance: {\"pointer\":\"/field1\"}
domain: \"validation\"
keyword: \"maxProperties\"
found: 2
required: 1
--- END MESSAGES ---
(org.mule.module.json.validation.JsonSchemaValidationException)." } }
Mule log