这个问题对我来说似乎有点太不明确了，但也许，这不管用吗？

// stream contains stuff like these in a flink tuple 
//(custom deserializer of array to tuple2???)
val jsonExample = """["foo", "bar"]"""

val stream: DataStream[Tuple2[JString, JString]] = ???
val filteredStream = stream.filter(x => x.getField(0).extract[String] == "foo")

如果你在写scala，最好不要使用flink元组。选择case类或者至少scala元组？

不用Map到元组，只需Map到case类并过滤掉不需要的内容：

// StreamingJob.scala

...

val filteredEvents = content
      .map(x => Event.toCaseClass(x))
      .filter(x => x.value == true)

...

// Event.scala

case class Event(
                  id: String,
                  value: Int,
                )
object Event {
  implicit val formats = DefaultFormats

  def toCaseClass(str: String) =
    parse(str).extract[Event]
}