code: protected void reportSyntaxError(int pos, String key, Object... args) {
          JCDiagnostic.DiagnosticPosition diag = new JCDiagnostic.SimpleDiagnosticPosition(pos);
          reportSyntaxError(diag, key, args);
      }
docs: Report a syntax using the given the position parameter and arguments,
  unless one was already reported at the same position.