How to process array of Struct in scala

Question

I have a dataframe with below schema

|-- matches: array (nullable = true)
 |    |-- element: struct (containsNull = true)
 |    |    |-- influencer: string (nullable = true)
 |    |    |-- frequency: long (nullable = true)
 |    |    |-- relevance: double (nullable = true)

I need to convert matches column to json format, but having difficulty is iterating struct elements.

Tried writing a udf to convert it to json, but unable to process ArrayElement. Can someone please suggest me a way to do it.

def convertToJSON = udf((value:  Array[ArrayElement]) => {
  Json.obj(
    "matches" -> value.map { x => Json.obj(
      "influencer" -> "",
      "overlap" -> "",
      "relevance" -> ""
    )
    }).toString()
})