Build info without the started date produces an unhelpful error

If build info is submitted without the started property, it will produce an unhelpful error:

  "errors" : [ {
    "status" : 500,
    "message" : "An unexpected error has occurred, please check Artifactory logs for further details."
  } ]

The other required fields (name and number) will produce a helpful error:

  "errors" : [ {
    "status" : 500,
    "message" : "Build name, number and date cannot be empty or null!"
  } ]

The same should occur for the started property. Also note there is no date property so the message needs to be updated.

To reproduce

1. Use curl to submit a build.json without the started property (see below)

• curl -u $ARTIFACTORY_USER_ACCESS -X PUT $ARTIFACTORY_URL/api/build -H "Content-Type: application/json" --upload-file build.json 

2. Observe the error

build.json

{
  "version" : "1.0",
  "name" : "MyBuild",
  "number" : "1",
  "agent" : {
    "name" : "N/A"
  }
}