<AssignVariable>
    <Name>target.url</Name>
    <Value>http://example.com/mypath?param=value&variable={apigee.variable}</Value>
    <Ref/>
</AssignVariable>

context.setVariable("target.url", mycompleteurl);

<TargetEndpoint>
    ...
    <HTTPTargetConnection>
        <LoadBalancer>
            <Server name="TargetServerABC"/>
        </LoadBalancer>
        <Path>/v1/YourPathHere/json.ws?{flow.company.queryparams}</Path>
    </HTTPTargetConnection>
</TargetEndpoint>