Is there api for getting source-machines from VRA.

Is there away to get a list of source machines that are data collected from a reservation using rest api.  Looking at the request in VRA its seems to be using a proxy URL to make a call to the VCO plugin api.  What is the easiest way make this rest call without so much indirection?

https://vra_server/vcac/gadgets/makeRequest?url=http://com.vmware.csp.component.iaas.proxy.provider.api.vproxy?source-machine

https://vra_server/vcac/gadgets/makeRequest?url=https%3A%2F%2Fcom.vmware.csp.component.iaas.proxy.provider.api.vproxy%2Fsource-machines%3F_dc%3D1469802112793%26actionId%3DFullClone%26platformTypeId%3DInfrastructure.CatalogItem.Machine.Virtual.vSphere%26loadTemplates%3Dtrue%26page%3D1%26start%3D0%26limit%3D30%26%2524orderby%3Dname&httpMethod=GET&headers=Accept%3Dapplication%252Fjson%26Content-Type%3Dapplication%252Fjson&postData=null&authz=&st=&contentType=JSON&numEntries=3&getSummaries=false&signOwner=true&signViewer=true&gadget=https%3A%2F%2Fcom.vmware.csp.component.cafe.composition.plugin.vproxy%2F%2Fgadget.xml&container=shell-default&bypassSpecCache=0&getFullHeaders=false&refresh=0