[BUG] operationId generated by odata makes generator fail

[Supernectar]

Description

Using the openapi-generator-cli command over a swagger.json file generated by an asp.net project that uses OData doesn't work.

When using OData in an asp.net project, the operationId field in the swagger.json file is autogenerated and sometimes includes a '$' symbol. This causes an exception to be thrown in the console.

Manually removing the '$' symbol gets rid of the exception but I want to be able to keep it programmatic without having to manually modify the file.

Steps to reproduce

Run the following command openapi-generator-cli generate -g jmeter -i swagger.json
swagger.json

{
    "openapi": "3.0.1",
    "info": {
        "title": "WebApplication1",
        "version": "1.0"
    },
    "paths": {
        "/Customers/$count": {
            "get": {
                "tags": [
                    "Customers"
                ],
                "operationId": "Customers/$count",
                "responses": {
                    "200": {
                        "description": "Success"
                    }
                }
            }
        }
    }
}

The following exception is thrown in the console:

[main] INFO  o.o.codegen.DefaultGenerator - Generating with dryRun=false
[main] INFO  o.o.c.ignore.CodegenIgnoreProcessor - No .openapi-generator-ignore file found.
[main] INFO  o.o.codegen.DefaultGenerator - OpenAPI Generator: jmeter (client)
[main] INFO  o.o.codegen.DefaultGenerator - Generator 'jmeter' is considered stable.
[main] INFO  o.o.codegen.utils.URLPathUtils - 'host' (OAS 2.0) or 'servers' (OAS 3.0) not defined in the spec. Default to [http://localhost] for server URL [http://localhost/]
[main] INFO  o.o.codegen.utils.URLPathUtils - 'host' (OAS 2.0) or 'servers' (OAS 3.0) not defined in the spec. Default to [http://localhost] for server URL [http://localhost/]
Exception in thread "main" java.lang.RuntimeException: Could not process operation:
  Tag: class Tag {
    name: Customers
    description: null
    externalDocs: null
}
  Operation: Customers/$count
  Resource: get /Customers/$count
  Schemas: {}
  Exception: Illegal group reference: group index is missing
	at org.openapitools.codegen.DefaultGenerator.processOperation(DefaultGenerator.java:1269)
	at org.openapitools.codegen.DefaultGenerator.processPaths(DefaultGenerator.java:1160)
	at org.openapitools.codegen.DefaultGenerator.generateApis(DefaultGenerator.java:609)
	at org.openapitools.codegen.DefaultGenerator.generate(DefaultGenerator.java:994)
	at org.openapitools.codegen.cmd.Generate.execute(Generate.java:519)
	at org.openapitools.codegen.cmd.OpenApiGeneratorCommand.run(OpenApiGeneratorCommand.java:32)
	at org.openapitools.codegen.OpenAPIGenerator.main(OpenAPIGenerator.java:66)
Caused by: java.lang.IllegalArgumentException: Illegal group reference: group index is missing
	at java.base/java.util.regex.Matcher.appendExpandedReplacement(Matcher.java:1030)
	at java.base/java.util.regex.Matcher.appendReplacement(Matcher.java:998)
	at java.base/java.util.regex.Matcher.replaceFirst(Matcher.java:1408)
	at org.openapitools.codegen.utils.StringUtils.lambda$camelize$1(StringUtils.java:141)
	at com.github.benmanes.caffeine.cache.BoundedLocalCache.lambda$doComputeIfAbsent$14(BoundedLocalCache.java:2406)
	at java.base/java.util.concurrent.ConcurrentHashMap.compute(ConcurrentHashMap.java:1908)
	at com.github.benmanes.caffeine.cache.BoundedLocalCache.doComputeIfAbsent(BoundedLocalCache.java:2404)
	at com.github.benmanes.caffeine.cache.BoundedLocalCache.computeIfAbsent(BoundedLocalCache.java:2387)
	at com.github.benmanes.caffeine.cache.LocalCache.computeIfAbsent(LocalCache.java:108)
	at com.github.benmanes.caffeine.cache.LocalManualCache.get(LocalManualCache.java:62)
	at org.openapitools.codegen.utils.StringUtils.camelize(StringUtils.java:135)
	at org.openapitools.codegen.utils.StringUtils.camelize(StringUtils.java:115)
	at org.openapitools.codegen.DefaultCodegen.addOperationToGroup(DefaultCodegen.java:5701)
	at org.openapitools.codegen.DefaultGenerator.processOperation(DefaultGenerator.java:1239)
	... 6 more

I expect the command to run properly and a jmeter file to be generated properly.

openapi-generator version

7.1.0 - installed via npm