如何使用groovy获取所需文档的objectID并将其存储在变量中？

@Grab('org.apache.httpcomponents:httpclient:4.5.13')

import org.apache.http.HttpEntity
import org.apache.http.HttpResponse
import org.apache.http.client.methods.HttpGet
import org.apache.http.impl.client.HttpClients
import org.apache.http.util.EntityUtils

def getDocumentId() {
    def url = "https://example.com/api/documents"
    def request = new HttpGet(url)
    def client = HttpClients.createDefault()
    def response = client.execute(request)
    
    if (response.getStatusLine().getStatusCode() == 200) {
        def entity = response.getEntity()
        def responseBody = EntityUtils.toString(entity)
        
        // 解析响应，提取objectID
        def objectId = parseResponse(responseBody)
        
        // 将objectID存储在变量中
        def documentId = objectId
        
        return documentId
    } else {
        throw new Exception("Failed to retrieve document ID")
    }
}

def parseResponse(responseBody) {
    // 解析响应，提取objectID的逻辑
    // ...
    // 返回objectID
}

// 调用函数获取文档的objectID并存储在变量中
def documentId = getDocumentId()