KTOR-6064 Fix documentation and message of NoTransformationFoundExcep…

…tion (#3733)

(cherry picked from commit 5307e6c)

ktor-client/ktor-client-core/common/src/io/ktor/client/call/HttpClientCall.kt

@@ -7,6 +7,7 @@ package io.ktor.client.call
 import io.ktor.client.*
 import io.ktor.client.request.*
 import io.ktor.client.statement.*
+import io.ktor.http.*
 import io.ktor.http.content.*
 import io.ktor.util.*
 import io.ktor.util.reflect.*
@@ -183,19 +184,24 @@ public class ReceivePipelineException(
 ) : IllegalStateException("Fail to run receive pipeline: $cause")
 
 /**
- * Exception representing the no transformation was found.
- * It includes the received type and the expected type as part of the message.
+ * Exception represents the inability to find a suitable transformation for the received body from
+ * the resulted type to the expected by the client type.
+ *
+ * You can read how to resolve NoTransformationFoundException at [FAQ](https://ktor.io/docs/faq.html#no-transformation-found-exception)
  */
-@Suppress("KDocMissingDocumentation")
 public class NoTransformationFoundException(
  response: HttpResponse,
  from: KClass<*>,
  to: KClass<*>
 ) : UnsupportedOperationException() {
- override val message: String? = """No transformation found: $from -> $to
- |with response from ${response.request.url}:
- |status: ${response.status}
- |response headers: 
- |${response.headers.flattenEntries().joinToString { (key, value) -> "$key: $value\n" }}
- """.trimMargin()
+ override val message: String? = """
+ Expected response body of the type '$to' but was '$from'
+ In response from `${response.request.url}`
+ Response status `${response.status}`
+ Response header `ContentType: ${response.headers[HttpHeaders.ContentType]}` 
+ Request header `Accept: ${response.request.headers[HttpHeaders.Accept]}`
+ 
+ You can read how to resolve NoTransformationFoundException at FAQ: 
+ https://ktor.io/docs/faq.html#no-transformation-found-exception
+ """.trimIndent()
 }