Cannot find usages of get() method in ResourceHandler.kt Readium class

I am trying to find how a library I am using reads files. I have narrowed down my search to the ResourceHandler.kt. ResourceHandler.kt is a read-only file generated by Readium which contains the method I am interested in. However, my problem arises whenever I try to find the usages of the method. When I use ctrl+click to see the usages, it gives a warning.

This is the method whose usages I am trying to find:

override fun get(uriResource: RouterNanoHTTPD.UriResource?, urlParams: 
Map<String, String>?,
                 session: IHTTPSession?): Response? {
    try {
        Log.v(TAG, "Method: ${session!!.method}, Uri: ${session.uri}")
        val fetcher = uriResource!!.initParameter(Fetcher::class.java)

        val filePath = getHref(session.uri)
        val link = fetcher.publication.linkWithHref(filePath)!!
        val mimeType = link.typeLink!!

        // If the content is of type html return the response this is done to
        // skip the check for following font deobfuscation check
        if (mimeType == "application/xhtml+xml") {
            return serveResponse(session, fetcher.dataStream(filePath), mimeType)
        }

        // ********************
        //  FONT DEOBFUSCATION
        // ********************

        return serveResponse(session, fetcher.dataStream(filePath), mimeType)
    } catch (e: Exception) {
        Log.e(TAG, "Exception in get", e)
        return newFixedLengthResponse(Status.INTERNAL_ERROR, mimeType, ResponseStatus.FAILURE_RESPONSE)
    }
}

This is the warning I receive:

fun get(uriResource: RouterNanoHTTPD.UriResource?, urlParams: Map<String, 
String>?, session: IHTTPSession?): Response? defined in 
org.readium.r2.streamer.server.handler.ResourceHandler overrides 
declarations in the following classes/interfaces: 
[Java] class DefaultHandler
[Java] interface UriResponder
[Java] class DefaultStreamHandler
 Do you want to find usages of the base declarations?

Weather I click Yes or No on the warning it does not show me any usages. I have tried to access the three classes/interfaces which the warning showed me but I am unable to find these files.

My question is: How can I find where this method is used and how can I access the classes/interfaces showed to me by the warning message.