How to pass array of string as parameters in swagger ui

Question

Below is the REST api which i want to document using Swagger UI

  @ApiOperation(
              nickname = "alertForBundleId",
              value = "alertForBundleId",
              notes = "",
              httpMethod = "GET")
  def alertForBundleId(
                @ApiParam(name = "mfr", value = "Manufacturer", required = true) @PathParam("mfr") mfr: String,
                @ApiParam(name = "col", value = "Columns", required = true) @QueryParam("col") cols: List[String])){...}

Here cols parameter is accepting List of string.
When i pass two elements for the list separating by new line, then its generates url like

?col=sysid%2Calert_id

while it should be like

?col=sysid&col=alert_id

it works well for single element list
Any help will be greatly appreciated.