message: derive default
diff: use casper_engine_grpc_server::engine_server::{ipc, state};
  use casper_types::{ProtocolVersion, U512};
  -#[derive(Debug)]
  +#[derive(Debug, Default)]
  pub struct SlashItem {
  validator_id: Vec<u8>,
  }
  @@ -12,14 +12,6 @@ impl SlashItem {
  }
  }
  -impl Default for SlashItem {
  - fn default() -> Self {
  - SlashItem {
  - validator_id: Default::default(),
  - }
  - }
  -}
  -
  impl From<SlashItem> for ipc::SlashItem {
  fn from(slash_item: SlashItem) -> Self {
  let mut item = ipc::SlashItem::new();
  @@ -28,7 +20,7 @@ impl From<SlashItem> for ipc::SlashItem {
  }
  }
  -#[derive(Debug)]
  +#[derive(Debug, Default)]
  pub struct RewardItem {
  validator_id: Vec<u8>,
  value: U512,
  @@ -44,15 +36,6 @@ impl RewardItem {
  }
  }
  -impl Default for RewardItem {
  - fn default() -> Self {
  - RewardItem {
  - validator_id: Default::default(),
  - value: Default::default(),
  - }
  - }
  -}
  -
  impl From<RewardItem> for ipc::RewardItem {
  fn from(reward_item: RewardItem) -> Self {
  let mut item = ipc::RewardItem::new();
  