ControllerExceptionHandler that uses existing org.springframework.http.ProblemDetail for custom exception handling

CloudStorageControllerSpec.java

import com.google.api.client.http.HttpHeaders
import com.google.api.client.http.HttpResponseException
import com.google.cloud.storage.StorageException
import org.spockframework.spring.SpringBean
import org.springframework.test.web.servlet.ResultActions

import static org.hamcrest.Matchers.is
import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get
import static org.springframework.test.web.servlet.result.MockMvcResultHandlers.print
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.content
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.jsonPath
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status

class CloudStorageControllerSpec extends BaseControllerISpec {

    static final MediaType PROBLEM_JSON_MEDIA_TYPE = new MediaType(
        MediaType.APPLICATION_PROBLEM_JSON.getType(), MediaType.APPLICATION_PROBLEM_JSON.getSubtype()
    )
    
    @SpringBean
    CloudStorageService cloudStorageService = Mock()

    void setup() {
        0 * _
    }

    def "get storage content by bucket - storage error"() {

        given:
        String bucket = "bucket"
        StorageException exception = new StorageException(404, "not found")

        when:
        ResultActions resultActions = mockMvc.perform(
            get("/storage/{bucket}", bucket)
                .accept(JSON_MEDIA_TYPE)
        )

        then: "exception with a valid HTTP code is thrown"
        1 * cloudStorageService.list(bucket) >> { throw exception }

        resultActions
            .andDo(print())
            .andExpect(status().isNotFound())
            .andExpect(content().contentType(PROBLEM_JSON_MEDIA_TYPE))
            .andExpect(jsonPath('$.title', is("Not Found")))
            .andExpect(jsonPath('$.detail', is(exception.message)))
            .andExpect(jsonPath('$.status', is(exception.code)))

        when:
        exception = new StorageException(0, "unknown")
        resultActions = mockMvc.perform(
            get("/storage/{bucket}", bucket)
                .accept(JSON_MEDIA_TYPE)
        )

        then: "exception with an invalid HTTP code is thrown"
        1 * cloudStorageService.list(bucket) >> { throw exception }

        resultActions
            .andDo(print())
            .andExpect(status().isInternalServerError())
            .andExpect(content().contentType(PROBLEM_JSON_MEDIA_TYPE))
            .andExpect(jsonPath('$.title', is("Internal Server Error")))
            .andExpect(jsonPath('$.detail', is(exception.message)))
            .andExpect(jsonPath('$.status', is(500)))
    }
}

ControllerExceptionHandler.java

import com.google.api.client.http.HttpResponseException;
import com.google.cloud.BaseServiceException;
import org.springframework.http.HttpStatus;
import org.springframework.http.ProblemDetail;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;

@ControllerAdvice
public class ControllerExceptionHandler {

    @ExceptionHandler
    ResponseEntity<?> handleCloudStorageException(BaseServiceException e) {

        return handleException(HttpStatus.resolve(e.getCode()), e);
    }

    @ExceptionHandler
    ResponseEntity<?> handleHttpResponseException(HttpResponseException e) {

        return handleException(HttpStatus.resolve(e.getStatusCode()), e);
    }

    ResponseEntity<?> handleException(HttpStatus status, Exception e) {

        if (status == null) {
            status = HttpStatus.INTERNAL_SERVER_ERROR;
        }

        ProblemDetail problemDetail = ProblemDetail.forStatusAndDetail(status, e.getMessage());

        return new ResponseEntity<>(problemDetail, status);
    }

}