[Mule] Add sessionVariable inside Groovy

addSessionVariable.xml

 <flow name="get:/user/{username}:api-config">
	<set-session-variable variableName="username" value="#[flowVars['username']]" doc:name="Session Variable"/>
	<set-payload value="#[payload]" doc:name="payload"/>
	<scripting:component doc:name="Groovy">
		<scripting:script engine="Groovy"><![CDATA[
    		def root = [:];
    		root.user = sessionVars['username']        	
    		def jsonContent = new groovy.json.JsonBuilder(root);
    		return jsonContent.toPrettyString();
		]]></scripting:script>
	</scripting:component>
	<logger message="LOGGER USER BY USERNAME:  #[username]" level="INFO" doc:name="Logger"/>
</flow>