private void evictMessages() {
    if (buffer.size() > 1) {
      buffer.remove(buffer.lastKey());
    } else if (buffer.size() == 1) {
      List<Message> messages = buffer.firstEntry().getValue();
      messages.remove(0);
    }
  }
Add message.

@param msgChainHeight the msg chain height
@param rawMsg the raw msg
consensus/common/src/main/java/org/hyperledger/besu/consensus/common/bft/statemachine/FutureMessageBuffer.java