fix:

1.https://gitee.com/tony2y/RuoYi-flowable/issues/I3VN42
2.https://gitee.com/tony2y/RuoYi-flowable/issues/I3TUB2

ruoyi-flowable/src/main/java/com/ruoyi/flowable/controller/FlowInstanceController.java

@@ -31,7 +31,7 @@ public class FlowInstanceController {
     @ApiOperation(value = "根据流程定义id启动流程实例")
     @PostMapping("/startBy/{procDefId}")
     public AjaxResult startById(@ApiParam(value = "流程定义id") @PathVariable(value = "procDefId") String procDefId,
-                                @ApiParam(value = "变量集合,json对象") @RequestBody @RequestParam(required = false) Map<String, Object> variables) {
+                                @ApiParam(value = "变量集合,json对象") @RequestBody Map<String, Object> variables) {
         return flowInstanceService.startProcessInstanceById(procDefId, variables);
 
     }

ruoyi-flowable/src/main/java/com/ruoyi/flowable/service/impl/FlowDefinitionServiceImpl.java

@@ -127,7 +127,7 @@ public class FlowDefinitionServiceImpl extends FlowServiceFactory implements IFl
     public AjaxResult readXml(String deployId) throws IOException {
         ProcessDefinition definition = repositoryService.createProcessDefinitionQuery().deploymentId(deployId).singleResult();
         InputStream inputStream = repositoryService.getResourceAsStream(definition.getDeploymentId(), definition.getResourceName());
-        String result = IOUtils.toString(inputStream, StandardCharsets.UTF_8);
+        String result = IOUtils.toString(inputStream, StandardCharsets.UTF_8.name());
         return AjaxResult.success("", result);
     }