Provide DataflowTemplate Constructor without the RestTemplate

[ghillert]

In order to improve the UX when using DataFlowTemplate, we should provide a constructor that does not require a RestTemplate to be passed in. Currently, not only must a RestTemplate be presently provided, but it also must fulfill the specific requirements of the DataFlowTemplate:

    @Bean
    public static RestTemplate restTemplate() {
        RestTemplate restTemplate = new RestTemplate();
        restTemplate.setErrorHandler(new VndErrorResponseErrorHandler(restTemplate.getMessageConverters()));
        for(HttpMessageConverter<?> converter : restTemplate.getMessageConverters()) {
            if (converter instanceof MappingJackson2HttpMessageConverter) {
                final MappingJackson2HttpMessageConverter jacksonConverter = (MappingJackson2HttpMessageConverter) converter;
                jacksonConverter.getObjectMapper().registerModule(new Jackson2HalModule());
                jacksonConverter.getObjectMapper().addMixIn(JobExecution.class, JobExecutionJacksonMixIn.class);
                jacksonConverter.getObjectMapper().addMixIn(JobParameters.class, JobParametersJacksonMixIn.class);
                jacksonConverter.getObjectMapper().addMixIn(JobParameter.class, JobParameterJacksonMixIn.class);
                jacksonConverter.getObjectMapper().addMixIn(JobInstance.class, JobInstanceJacksonMixIn.class);
                jacksonConverter.getObjectMapper().addMixIn(ExitStatus.class, ExitStatusJacksonMixIn.class);
                jacksonConverter.getObjectMapper().addMixIn(StepExecution.class, StepExecutionJacksonMixIn.class);
                jacksonConverter.getObjectMapper().addMixIn(ExecutionContext.class, ExecutionContextJacksonMixIn.class);
                jacksonConverter.getObjectMapper().addMixIn(StepExecutionHistory.class, StepExecutionHistoryJacksonMixIn.class);
            }
        }
        return restTemplate;
    }

This configuration is taken from the Spring Cloud Dataflow Shell module.

[ghillert]

See also: pring-cloud/spring-cloud-dataflow/issues/871