Java 8，可选。引发异常，并重新引发异常，防止 null

问：

我感到困惑（缺乏理解），试图将我的代码的某些部分翻译成 Java 8。Optional

第一个示例模拟代码

    private void privateMethodOne(CustomRequesDto customRequesDto) {

        // Some lines of code

        ResponseEntity<CustomResponseDto> responseEntity;
        try {
            responseEntity = callWebClientRequestOne();
        } catch (Exception e) {
            RuntimeException ex = new CustomClientException(customRequesDto, e.getMessage());
            log.error(ex.getMessage());
            throw ex;
        }


        if (responseEntity.getBody() == null) {
            throw new CustomResponseException("myMessage");
        }
        CustomResponseDto customResponseDto = responseEntity.getBody();
        return Optional.ofNullable(customResponseDto).map(CustomResponseDto::getProperty).orElse(null);

    }

在第一个示例模拟代码中，我想将这一行减少到一行中，使用（如果可能的话）Optional

        if (responseEntity.getBody() == null) {
            throw new CustomResponseException("myMessage");
        }
        CustomResponseDto customResponseDto = responseEntity.getBody();
        return Optional.ofNullable(customResponseDto).map(CustomResponseDto::getProperty).orElse(null);

如何在单行中做同样的事情？

第二个示例模拟代码

    private void privateMethodTwo(CustomRequesDto customRequesDto) {

        // Some lines of code

        ResponseEntity<byte[]> responseEntity = null;
        try {
            responseEntity = callWebClientRequestTwo();
        } catch (Exception e) {
            mapExceptions.put(customRequesDto, e.getMessage());
        }

        try {
            if (responseEntity != null && responseEntity.getBody() == null) {
                throw new CustomResponseException("myMessage");
            }
        } catch (Exception e) {
            mapExceptions.put(someObject, e.getMessage());
        }

        // continue the executions
    }

第二个示例模拟代码，我想将这一行减少到一行中，使用（如果可能的话）Optional

        try {
            if (responseEntity != null && responseEntity.getBody() == null) {
                throw new CustomResponseException("myMessage");
            }
        } catch (Exception e) {
            mapExceptions.put(someObject, e.getMessage());
        }

如何在单行中执行相同的操作？