Function generate_action_diffs 

pub fn generate_action_diffs<A: Actionlike>(
    global_action_state: Option<Res<'_, ActionState<A>>>,
    action_state_query: Query<'_, '_, (Entity, &ActionState<A>)>,
    previous_action_state: Local<'_, SummarizedActionState<A>>,
    action_diff_messages: MessageWriter<'_, ActionDiffMessage<A>>,
)

Generates an Messages stream of ActionDiffs from every ActionState.

This system is not part of the InputManagerPlugin and must be added manually. Generally speaking, this should be added as part of PostUpdate, to ensure that all inputs have been processed and any manual actions have been sent.