Add support for following redirects in OPTIONS request

Author: sunkup

src/main/kotlin/at/bitfire/dav4jvm/DavResource.kt

@@ -151,22 +151,30 @@ open class DavResource @JvmOverloads constructor(
 
     /**
      * Sends an OPTIONS request to this resource without HTTP compression (because some servers have
-     * broken compression for OPTIONS). Doesn't follow redirects.
+     * broken compression for OPTIONS). Follows up to [MAX_REDIRECTS] redirects when set.
      *
+     * @param followRedirects whether redirects should be followed (default: *false*)
      * @param callback called with server response unless an exception is thrown
      *
      * @throws IOException on I/O error
      * @throws HttpException on HTTP error
      * @throws DavException on HTTPS -> HTTP redirect
      */
     @Throws(IOException::class, HttpException::class)
-    fun options(callback: CapabilitiesCallback) {
-        httpClient.newCall(Request.Builder()
+    fun options(followRedirects: Boolean = false, callback: CapabilitiesCallback) {
+        val callBlock = {
+            httpClient.newCall(Request.Builder()
                 .method("OPTIONS", null)
                 .header("Content-Length", "0")
                 .url(location)
                 .header("Accept-Encoding", "identity")      // disable compression
-                .build()).execute().use { response ->
+                .build()).execute()
+        }
+        val response = if (followRedirects)
+            followRedirects(callBlock)
+        else
+            callBlock()
+        response.use {
             checkStatus(response)
             callback.onCapabilities(
                 HttpUtils.listHeader(response, "DAV").map { it.trim() }.toSet(),