Spring and Camel makes this quite easy (same solution can be used in Camel-K too). Here is an example of the use of custom property in a route

appilcation.properties

# Greeting
greeting = Hello World

# Timer
timer.period = 2000

Example route with the above properties

from("timer:hello?period={{timer.period}}")
     .log("{{greeting}}");

The route will now print out “Hello World” every 2 seconds

Tested on Apache Camel 3.20.0, SpringBoot 2.7.6, Java 11.0.18 and Ubuntu 20.04.4 LTS