Add headless mode: - Checks for headless=true setting in jsonrpc.properties. - Or if Java system property java.awt.headless is true Shutdown hook tries to exit gracefully if ctrl-c or kill signal is trapped.
Add headless mode:
- Checks for headless=true setting in jsonrpc.properties.
- Or if Java system property java.awt.headless is true
Shutdown hook tries to exit gracefully if ctrl-c or kill signal is trapped.

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