public static finalStringCOMMAND_KEY_INPUT_REQUEST
Requests from a client - what an operator reads as "how much traffic is this node taking".
Kept as an alias of FcCommandKeys.INPUT_REQUEST rather than replaced by it: this is
where the key has always been referenced from, and the indirection costs nothing.
Overridden by every Frontcache command. The base implementation signals "no fallback available",
which FcCommand.execute() turns into an FcCommandException - the HystrixRuntimeException
equivalent.