Salesforce REST APEX 代码的 requestURI.lastIndexOf('/')+1) 中的 meaning/significance of +1 是什么

What is meaning/significance of +1 in requestURI.lastIndexOf('/')+1) of Salesforce REST APEX Code

以下 Salesforce REST APEX 代码中的 +1 meaning/significance 是什么

            @HttpPatch
                global static ID updateCaseFields() {
                    RestRequest request = RestContext.request;
                    String caseId = request.requestURI.substring(
                        request.requestURI.lastIndexOf('/')+1);
                    Case thisCase = [SELECT Id FROM Case WHERE Id = :caseId];
                    // Deserialize the JSON string into name-value pairs
                    Map<String, Object> params = (Map<String, Object>)JSON.deserializeUntyped(request.requestbody.tostring());
                    // Iterate through each parameter field and value
                    for(String fieldName : params.keySet()) {
                        // Set the field and value on the Case sObject
                        thisCase.put(fieldName, params.get(fieldName));
                    }
                    update thisCase;
                    return thisCase.Id;
                }    
            }

+1 在 substring() 函数中,因此它在请求 uri 中的“/”的最后一个索引处加一,以获取案例 ID。

ex) URI 通常如下所示:

https://<instance>.salesforce.com/Case/<some_case_id>

+1 允许子字符串函数查看最后一个正斜杠“/”之后的位置,以获取 uri 末尾的案例 ID。