Indicates whether this VPA is ready for use by clients. An VpaAvailabilityState.AVAILABLE VPA should provide valid data as results when its other properties such as vpaAuthenticationStatus, vpaSettings, dialogueState are accessed. This VPA should not be in the VpaAvailabilityState.AVAILABLE state if it cannot provide valid results when these properties are queried. It should also not set itself to this state if it is, for example, busy initializing itself or in an erroneous state which prevents it from being used for any API call.