/strings/{id}/raw throws cast exception

I am using hawkular-metrics 0.18.0. When calling /strings/

/raw i get a valid response but see an error on the server.

• Log from client: https://gist.github.com/garethahealy/e4af23d8c091efcae0729e15d9e2db8a
• Log from server: https://gist.github.com/garethahealy/24c4238959984df4420f1b522bea51f0

This only happens on the first call.