code: private void checkRequiredCreateDiscussionArguments(String body,
              String positionBaseSha, String positionStartSha, String positionHeadSha) {
          if (body == null || body.isEmpty()) {
              throw new IllegalArgumentException("Missing required argument 'body'!");
          } else if (positionBaseSha == null || positionBaseSha.isEmpty()) {
              throw new IllegalArgumentException("Missing required argument 'positionBaseSha'!");
          } else if (positionStartSha == null || positionStartSha.isEmpty()) {
              throw new IllegalArgumentException("Missing required argument 'positionStartSha'!");
          } else if (positionHeadSha == null || positionHeadSha.isEmpty()) {
              throw new IllegalArgumentException("Missing required argument 'positionHeadSha'!");
          }
      }
docs: Check if the required arguments to create a discussion are present and
  contain values.
  
  @param body              The content of a discussion.
  @param positionBaseSha   The base commit SHA in the source branch.
  @param positionStartSha  The SHA referencing commit in target branch
  @param positionHeadSha   The SHA referencing HEAD of this merge request