docs: public static boolean lambdaParamIsImplicitlyTyped(VariableTree lambdaParameter) {
      // kind of a hack; the "preferred position" seems to be the position
      // of the variable name.  if this differs from the start position, it
      // means there is an explicit type declaration
      JCDiagnostic.DiagnosticPosition diagnosticPosition =
          (JCDiagnostic.DiagnosticPosition) lambdaParameter;
      return diagnosticPosition.getStartPosition() == diagnosticPosition.getPreferredPosition();
    }