Why Custom Work Item does not work in JBPM Business Central?

Question

I created custom work item for jBPM 7.74.1.Final. It is based on "core" Rest Work Item (https://github.com/kiegroup/jbpm/tree/main/jbpm-workitems/jbpm-workitems-rest). I added OAuth2 authentication there. It works when I use it in Eclipse jBPM plugin. But it does not work in Business Central. There is an error in log:

11:41:04,021 ERROR [org.kie.workbench.common.stunner.bpmn.backend.workitem.WorkItemDefinitionParser] (default task-49) The work item has an invalid name [ Rest2].It must contain words only, skipping it.

Any idea what is the cause of this error?

The way how I add it to the Business Central:

1. BC homepage, click Admin (upper right corner)
2. Custom Task Administration
3. Click Add Custom Task and upload the *.jar with the work item
4. Wtich toggle to "ON"
5. Go to my project
6. Go to "Settings" tab
7. Go to "Custom Task" part and click on "Install"
8. Create a new business process in my project
9. BUG: I can not see my work item

Rest2.wid file (generated automatically during maven build):

    [
            [
                "name" : "Rest2",
                "displayName" : "Rest2",
                "category" : "jbpm-workitem-rest2",
                "description" : "",
                "defaultHandler" : "mvel: new com.cross_ni.cross.jbpm.workitem.rest2.REST2WorkItemHandler()",
                "documentation" : "jbpm-workitem-rest2/index.html",
    
                "parameters" : [
                                    "Cookie" : new StringDataType()
                    ,"ConnectTimeout" : new StringDataType()
                    ,"ResultClass" : new StringDataType()
                    ,"ContentType" : new StringDataType()
                    ,"AcceptCharset" : new StringDataType()
                    ,"Headers" : new StringDataType()
                    ,"AuthUrl" : new StringDataType()
                    ,"CookiePath" : new StringDataType()
                    ,"Method" : new StringDataType()
                    ,"ReadTimeout" : new StringDataType()
                    ,"Url" : new StringDataType()
                    ,"ContentTypeCharset" : new StringDataType()
                    ,"HandleResponseErrors" : new StringDataType()
                    ,"ContentData" : new StringDataType()
                    ,"Username" : new StringDataType()
                    ,"Content" : new StringDataType()
                    ,"AcceptHeader" : new StringDataType()
                    ,"AuthType" : new StringDataType()
                    ,"Password" : new StringDataType()
    
                ],
                "results" : [
                                    "Result" : new StringDataType()
    
                ],
                "mavenDependencies" : [
                                     "com.cross_ni.cross:jbpm-workitem-rest2:1.0.0-SNAPSHOT"
    
                ],
                "icon" : "defaultresticon.png"
    
            ]
    
    ]

Thank you.