Getting Platform declaration clash when using Interface in kotlin

I'm converting some classes in Java to kotlin and I'm running into compile errors when trying to inherit from an interface:

Platform declaration clash: The following declarations have the same JVM signature (getContentID()Ljava/lang/String;):

public open fun get-content-id (): String? public open fun getContentId(): String?

Here is the interface:

interface Media {
  val contentId: String

  val displayRunTime: String

  val genres: List<String>

  val programId: String

  val runTime: String

  val type: String
}

here is the class:

class Airing : Media {
  override val contentId: String? = null
  override val displayRunTime: String? = null
  override val genres: List<String>? = null
  override val programId: String? = null
  override val runTime: String? = null
  override val type: String? = null

  override fun getContentId(): String? {
    return contentId
  }

I'm super new to kotlin.