How to add dynamic uuid to apigee proxies? - apigee

Question

What should be of uuid instead of {java.util.UUID.randomUUID()} to get a random UUID in every request sent to backend ?
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<AssignMessage async="false" continueOnError="false" enabled="true"
name="HeaderAddition">
<DisplayName>HeaderAddition</DisplayName>
<Properties/>
<Add>
<Headers>
<Header name="uuid">{java.util.UUID.randomUUID()}</Header>
</Headers>
</Add>
<IgnoreUnresolvedVariables>true</IgnoreUnresolvedVariables>
<AssignTo createNew="false" transport="http" type="request"/>
</AssignMessage>

Answer 1

I have got the solution .
I have added a Javascript in the preflow to generate the uuid.Then created a assign message policy to have that variable in the request.
JS:
function generateUUID() { // Public Domain/MIT
var d = new Date().getTime();
if (typeof performance !== 'undefined' && typeof performance.now === 'function'){
d += performance.now(); //use high-precision timer if available
}
return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function (c) {
var r = (d + Math.random() * 16) % 16 | 0;
d = Math.floor(d / 16);
return (c === 'x' ? r : (r & 0x3 | 0x8)).toString(16);
});
}
var uuid = generateUUID();
context.setVariable('x-apigee-uuid', uuid);
Assign Message Policy:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<AssignMessage async="false" continueOnError="false" enabled="true"
name="HeaderAddition-123">
<DisplayName>HeaderAddition-123</DisplayName>
<Add>
<Headers>
<Header name="uuid">{x-apigee-uuid}</Header>
</Headers>
</Add>
<IgnoreUnresolvedVariables>true</IgnoreUnresolvedVariables>
<AssignTo createNew="false" transport="http" type="request"/>
</AssignMessage>