Use ktor's HttpHeaders everywhere, and add warning about ktor-okhttp in README

README.md

@@ -18,6 +18,15 @@ For questions, suggestions etc. use [Github discussions](https://github.com/bitf
 We're happy about contributions, but please let us know in the discussions before. Then make the changes
 in your own repository and send a pull request.
 
+> [!NOTE]
+> dav4jvm is currently being rewritten to use ktor instead of OkHttp to allow Kotlin Multiplatform support, and other engines.
+> 
+> In the mean time, there are two packages available:
+> - `at.bitfire.dav4jvm.okhttp` (the current one, using OkHttp, JVM only)
+> - `at.bitfire.dav4jvm.ktor` (new package, uses ktor, supports Kotlin Multiplatform)
+> 
+> There's some common code shared between both packages. This code may contain references to ktor, so do not exclude the dependency, even if you are only using okhttp.
+
 
 ## Installation
 

src/main/kotlin/at/bitfire/dav4jvm/property/caldav/ScheduleTag.kt

@@ -14,7 +14,6 @@ import at.bitfire.dav4jvm.Property
 import at.bitfire.dav4jvm.PropertyFactory
 import at.bitfire.dav4jvm.QuotedStringUtils
 import at.bitfire.dav4jvm.XmlReader
-import at.bitfire.dav4jvm.property.webdav.GetETag
 import io.ktor.client.statement.HttpResponse
 import io.ktor.http.HttpHeaders
 import okhttp3.Response

src/main/kotlin/at/bitfire/dav4jvm/property/webdav/GetETag.kt

@@ -37,7 +37,7 @@ data class GetETag(
             response.headers[HttpHeaders.ETag]?.let { GetETag(it) }
 
         fun fromResponse(response: Response) =
-            response.header("ETag")?.let { GetETag(it) }
+            response.header(HttpHeaders.ETag)?.let { GetETag(it) }
     }
 
     /**