Where to put cerrtificate file

I read about Kotlin managment of SSL Certificate, but I don’t know where to put the cert file in order to be found:

// Load CAs from an InputStream
// (could be from a resource or ByteArrayInputStream or …)
val cf: CertificateFactory = CertificateFactory.getInstance(“X.509”)
// From https://www.washington.edu/itconnect/security/ca/load-der.crt
val caInput: InputStream = BufferedInputStream(FileInputStream(“load-der.crt”))

Where am I going to put “load-der.crt” to be found?
Thank you!