code: @BuilderMethod
      public void setHttpHeaders(@NonNull Map<String, String> headers) {
          this.httpHeaders.clear();
          this.httpHeaders.putAll(headers);
      }
docs: Set custom HTTP headers to be sent by the provided {@link org.acra.sender.HttpSender}
  This should be used also by third party senders.
  
  @param headers A map associating HTTP header names to their values.