is there any built-in util method from converting an outputstream to an inputstream?

https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.io/ 🔝 available I/O API in Kotlin (plus the Java APIs) By converting output stream to input stream do you mean transmitting the data received from the input to the output ? If so you could do something like:

input.copyTo(output)

the other way around 🙂