REST API call node generating an error during generic-resource-assingment. vfmodule-topology-operation-assign

looks like its because prop.restapi.preloadinformation is null

2018-09-15T13:03:04,367 | INFO  | qtp1173655953-125 | RestapiCallNode                  | 227 - org.onap.ccsdk.sli.plugins.restapi-call-node-provider - 0.3.0.SNAPSHOT | SvcLogicGraph [module=GENERIC-RESOURCE-API, rpc=vf-module-topology-operation-assign, mode=sync, version=1.4.0-SNAPSHOT, md5sum=65271ef0dba4ed994ec956a50e6775cc] - 1 (block) | Parameter restapiUrl: http://localhost:8181HV-VES-Simulator-VF-20180915a1/vf-module

<execute plugin='org.onap.ccsdk.sli.plugins.restapicall.RestapiCallNode' method='sendRequest' >
<parameter name='restapiUrl' value="`$prop.controller.url + $prop.restapi.preloadinformation + $vf-module-topology-operation-input.vf-module-request-input.vf-module-name + '/vf-module'`" />
<parameter name='restapiUser' value='`$prop.controller.user`' />
<parameter name='restapiPassword' value='`$prop.controller.pwd`' />
<parameter name='format' value='json' />
<parameter name='httpMethod' value='GET' />
<parameter name="responsePrefix" value="mdsal-preload" />