import okhttp3.internal.checkOffsetAndCount
import okhttp3.internal.chooseCharset
import okio.BufferedSink
import okio.ByteString
import okio.FileSystem
import okio.HashingSink
import okio.Path
import okio.blackholeSink
import okio.buffer
import okio.source

abstract class RequestBody {
  /** Returns the Content-Type header for this body. */
  abstract fun contentType(): MediaType?

  /**