// Обёртка над Zstd JNI
import org.apache.commons.compress.compressors.zstandard.ZstdCompressorInputStream;
// ...
if (
  containerRequestContext
    .getHeaders()
    .getFirst("Content-Encoding")
    .equals("zstd")
) {
  containerRequestContext
    .setEntityStream(ZstdCompressorInputStream(
      containerRequestContext.getEntityStream()
    ))
}

import Foundation
import ZSTD
final class ZSTDRequestSerializer {
    private let compressionLevel: Int32
    init(compressionLevel: Int32) {
        self.compressionLevel = compressionLevel
    }
    func requestBySerializing(request: URLRequest, parameters: [String: Any]?) throws -> URLRequest? {
        guard let mutableRequest = (request as NSURLRequest).mutableCopy() as? NSMutableURLRequest else {
            return nil
        }
        // ...
        mutableRequest.addValue("zstd", forHTTPHeaderField: "Content-Encoding")
        if let parameters = parameters {
            let jsonData = try JSONSerialization.data(withJSONObject: parameters, options: [])
            let processor = ZSTDProcessor(useContext: true)
            let compressedData = try processor.compressBuffer(jsonData, compressionLevel: compressionLevel)
            mutableRequest.httpBody = compressedData
        }
        return mutableRequest as URLRequest
    }
}

// Тут перехватываем отправку события через interceptor и подменяем оригинальный body на сжатый если это запрос к events
override fun intercept(chain: Interceptor.Chain): Response {
   val originalRequest = chain.request()
   return if (originalRequest.url.toString()
               .endsWith("/events")) {
      val compressed = originalRequest.newBuilder()
            .header("Content-Encoding", "zstd")
            .method(originalRequest.method, zstd(originalRequest.body))
            .build()
      chain.proceed(compressed)
   } else {
      chain.proceed(chain.request())
   }
}
// Метод сжатия, берет requestBody и возвращает сжатый
private fun zstd(requestBody: RequestBody?): RequestBody {
   return object : RequestBody() {
      override fun contentType(): MediaType? = requestBody?.contentType()
      override fun contentLength(): Long = -1 //We don't know the compressed length in advance!
      override fun writeTo(sink: BufferedSink) {
         val buffer = Buffer()
         requestBody?.writeTo(buffer)
         sink.write(Zstd.compress(buffer.readByteArray(), compressLevel))
      }
   }
}