@anil Thank you for reaching out to Microsoft Q&A. Sorry for the delay in response.
Yes, you can use a custom key instead of default "/application/config.message" showed in the example. Check Spring Cloud for Azure starter App Configuration that has property spring.cloud.azure.appconfiguration.stores[0].selects[0].key-filter with default "/application/*". You can make it either "/myappname/" or "/${spring.application.name}/" based on your need.
The key-filter value is a prefix added onto the keys and is trimmed from the keys in use (same is described here and check out for all of the details on how the Spring Cloud Azure App Configuration library works). I hope this answers your question and feel free to add if you have any questions. I would be happy to assist you.
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